of the trabeculae of this system can be readily followed. This system is thought to consist of separate cells and not to present syncytial character. McCotter (Anat. Rec., x) has described and figured three human hearts with persistent left superior vena cavae, each presenting a rare condition. He traces their embryonic origin and development. Wahl (Am. Jour. Anat., xviii) has shown that the blood supply of the mammary gland during development and rest is in the main secondary to the blood supply of the skin and subcutaneous muscles, while during functional activity it is dependent on an extension of the vessels of the ducts and is thus more independent.

bryos. He concludes that red blood cells can develop in the anterior mesenchyme or in the anterior vessels under conditions in which the heart pulsations could not have accounted for their position, and not only in the stem veins and in blood islands found in the caudal end of the embryo. Arey (Science, xxxxiv) contributes a study of the form of the mammalian red blood cell. The evidence gained from an examination of drawn blood diluted in human serum, and of circulating blood in non-anesthetized living mammals justifies the conclusion that the biconcave disc represents the normal shape, concaveconvex cups an occasional modifica tion. Schulte (Am. Jour. Anat., xx) reports on a study of the fusion of Nervous System and Organs of the cardiac anlagen and the forma- Special Senses.-Weed (Anat. Rec., x) tion of the cardiac loop in the do- presents an investigation on the formestic cat, giving a detailed account mation of the subarachnoid spaces. based on wax-plate reconstructions The fluid in these spaces was replaced of successive stages of development in living pig embryos with isotonic of the myocardial mantle and the en- solutions of potassium ferrocyanide dothelial tube. The fusion of the and iron-ammonium citrate, later preformer is accomplished with the aid cipitated. Evidence is presented of the middle cardiac plate, which is showing that the first extraventricureduced to a ridge and makes the in- lar spread of the fluid, in pig emterventricular septum. The endo- bryos, occurs at the 14 mm. stage; a cardium originates as does endothe- total filling of the perimedullary lium in other parts of the body, de- spaces is attained at the 26 mm. veloping from the mesenchyme formed stage. The formation of these spaces in loco. The early mesenchyme con- is connected with a dilation of the sists of separate cells or groups of mesenchymal spaces. Allen (Jour. cells, vacuoles appear, enlarging the Comp. Neur., xxvi) presents observacontaining cells to endothelium, the tions on the development of the spinal resulting vesicles uniting to form cord and medulla of cyclostomes with endothelial tubes, which fuse to form special reference to the formation and the endothelial heart tube. Bullard expansion of the roof plate, showing (Am. Jour. Anat., xix) has shown that in most vertebrates three stages that the cardiac muscle of mammals of expansion should be recognized: contains a nutritive reserve of neutral (1) enlargement of the dorsal portion fat in the form of droplets arranged of the embryonic central canal owing longitudinally in the sarcoplasm. to migration upwards and outwards This is decreased in inanition. Phos- of certain of the roof-plate cells; (2) pholipin found in the interstitial | enlargement of the canal owing to ingranules-mitochondria is not appreciably decreased by inanition. Visible neutral fat is of normal occur rence in the atrioventricular bundle. King (ibid.) gives a detailed description of observations made after injecting with Prussian blue or India ink the sheaths of the sinoventricular system, mainly in the bovine heart. Ön successful injection of the sheath of the sinoventricular system, the course and the distribution

creased pressure of the cerebrospinal fluid; (3) a final stage of expansion due to the appearance of the pontine flexure. Bailey (ibid.) contributes on the morphology of the roof plate of the forebrain and the lateral choroid plexuses in the human embryo. The regions involved were reconstructed in embryos of 19, 27.8 and 32.1 mm. crown-rump length. The choroid plexuses of the lateral ventricles were found to be composed of

two distinct portions. The neuroporic termination of the part played by the recess could not be determined with myelin in reducing the water content certainty; the paraphysal arch and of the mammalian nervous system velum transversum could be traced and states that the progressive dimin embryos of 32 mm. length. The inution in the water content of epiphysis shows indication of the the entire brain and spinal cord is presence of the homologue of the mainly due to an accumulation of pineal vesicle of lower vertebrates. myelin, both diminution of the perÎn a further contribution on the mor- centage of the water and myelin forphogenesis of the choroid plexus mation being a function of age. Kee(ibid.), this author considers its for- gan (ibid.) reports on a study on the mation in the turtle and reviews crit- fissuration and cerebral cortex areas ically the literature. The observations of the Plains Indian brain, finding support the conclusion that the lat- that the Indian brain presents in eral telencephalic plexus arises from practically all features a high type of the roof plate of the telencephalon cerebrum; the great asymmetry of to the tænia fornicis and in higher the two hemispheres in fissuration forms it oversteps the tænia fornicis in the brain especially studied eviand the medial hemisphere wall is dencing a highly specialized cerebrum. invaginated; this latter portion dom- McCotter (Anat. Rec., x) has investiinates in development as the verte- gated the length and extent of the brate scale is ascended. Burr (ibid.) human spinal cord, finding that its notes that the forebrain of Ambly- average length in the male is 44.79 stoma will not regenerate when its cm. and in the female 41.8 cm. There functional endorgan is completely ex- is no definite relation between length tirpated, but will regenerate if the of spinal cord and height of the subnasal placode is not extirpated, this ject and no definite ratio between acting as a stimulus to the regenerat- length of vertebral axis and the ing telencephalon through the in- spinal cord. The highest level at growth of the olfactory nerves. He which the spinal cord was found to has also studied (Jour. Exp. Zoöl., terminate was the level of the middle xx) the effect of removal of the nasal of the body of the 12th dorsal verpits in Amblystoma and finds that tebra, and the lowest level, the inthe absence of the nasal pits results ferior border of the second lumbar in a collapse of the cartilage sur- vertebra. Johnston (Jour. Comp. rounding the nasal sac and a reduc- Neur., xxvi) presents evidence showtion of the size of the telencephalon ing that in reptilian brains there is on the affected side, the removal of located a comma-shaped area involvthe pit depriving the developing braining the rostral and lateral border of of a stimulus necessary for its complete development, evident particularly after the olfactory organ on the unoperated side becomes functional. Coghill (Jour. Comp. Neur., xxvi) reports on a study of the afferent nervous system of the head of Amblystoma embryos with a view of correlating anatomic structure and physiologic activity. He presents a detailed study of the development of the afferent head nerves and organs of special sense in a non-motile stage, early flexure stage, coil-reaction stage and early swimming stage. The entrance of the receptor field of the trigeminal nerve into function is closely correlated with the extension of its root fibers into the motor centers in the lower part of the medulla. Donaldson (ibid.) reports on a de

the pallium, which may be regarded as definite sensory and motor areas in the sense in which these are commonly used with reference to the mammalian pallium. Jenkins (Anat. Rec., x) presents the results of an investigation on the form of the inferior olive. This mass of the gray matter of the medulla was reconstructed in human embryos of different ages. Figures of the models obtained are given with a description of the convolutions as presented in the models. Atwell (ibid.) reports on the relations of the chorda dorsalis to the hypophysis. In rabbit embryos the entoderm can not be said to contribute to the formation of the hypophysis. In the bird there is observed a small entodermal increment to the hypophysis, derived from the

notochord, but this is an accidental | contribution he describes in detail a union of parts and not to be regarded model so constructed as to simulate as an entodermal contribution to the the chief receptive and vibratory hypophysis. Koch (Jour. Comp. structures of the cochlea, and was Neur., xxvi) reports on a study of able to obtain corroborative evidence the III, IV, V, VI, IX, XI and XIIth of selective tectorial membrane vibracranial nerves, mainly as observed in tion. Arey (Jour. Comp. Neur., XXV) pyridin-silver preparations. He finds presents a very useful review of the unmyelinated fibers in the V, VI, IX important literature dealing with the and XIIth cranial nerves, probably effect of light on the retinal elements, derived from the sympathetic in the deducing from the present status of VI, IX and XIIth. Kocher (ibid.) our information concerning movehas investigated the effect of activity ments of the visual cells and retinal on the structure of nerve cells. There pigments the general conclusion that was found to be no difference in these movements have a certain sigsize of cells or nuclei resulting from nificance in connection with light peractivity and no qualitative differ- ception, but they are to be interpreted ences in histological character be- only in terms of protoplasmic retween fatigued and resting nerve sponses to definite stimulating agents. cells. Ranson and Billingsley (Am. He has sought also (ibid., xxvi) to Jour. Phys., xxxxi) have by electrical determine experimentally the presstimulation of the floor of the fourth ence of efferent nerves to the eye conventricle in cats determined a re- trolling the movements of visual cells gion in the fovea inferior producing and retinal pigments. Evidence is rise in blood pressure, and a de- presented showing the existence of pressor point causing a fall in blood efferent nerve fibers in the optic pressure in the area postrema just nerve and probably in the ciliary aulateral to the obex. These observers tonomic nerves, through the balanced (ibid.) present experimental and action of which movement in the anatomic evidence which warrants retinal pigment and visual cells is the conclusion that pain and tempera- alone possible. Also (ibid.) in studyture sensations aroused by objects ing the changes in the rod visual cells under 22° or over 40° C are mediated of the frog due to action of light it by afferent non-myelinated fibers en- was observed that no movement of tering Lissauer's tract and ending in the nuclei of the rod visual cells, due the substantia gelatinosa. Streeter to action of light, is demonstrable (Am. Jour. Anat., xix) presents ob- and that the myoid of these cells servations bearing on the develop- elongates and becomes tenuous in ment and vascular drainage of the light and shortens in the dark. In a endolymphatic sac and its topo- further study (ibid.) it is shown that graphic relation to the transverse both in light and in darkness the sinus. In 30 mm. human embryos the retinal pigment of fishes shows greatmain features in the differentiation er expansion at low than at high of the saccus endolymphaticus are temperatures. Cone myoids of fishes obtained and its topographic relations shorten at low temperature in the are practically as in the adult; lying dark and lengthen at high temperaagainst the median or dorso-median ture, as also the myoids of rods. Corwall of the transverse sinus, covered relation between length of rod myoid by the dura mater. Throughout the and temperature was not detected in greater part of fetal life the sac is the frog, neither in darkness nor in surrounded by a vascular plexus, well the light. Detweiler (Jour. Exp. developed in embryos of 50 mm. Zool., xx) reports on the effect of length. In embryos of 100 mm. light on the retina of lizards and torlength and over, a few principal chan- toises. The retinae of the former posnels connect this vascular plexus with sess only cone visual cells. Light the transverse sinus. Hardesty causes a migration of the pigment and (ibid., xviii) has in a number of pub- a contraction of the cones, even after lications endeavored to show that the the optic nerve is cut. Electrical stim1 membrane of the cochlea is ulation of enucleated eyes causes a ibratory structure. In this movement of the pigment.

nomena

PHYSIOLOGY AND PHARMACOLOGY

S. J. MELTZER

The

Blood and Circulation.-The phe- | phere. But stimulation results even has of hibernation been when the oxygen pressure falls to six ascribed to the accumulation of CO2 per cent. of an atmosphere.-The morin the blood. Rasmussen (J. P., phological changes in the tissues of xxxix, 20) investigated the blood the rabbit as a result of reduced oxgases of the woodchuck during ac- idations have been studied by Martin, tivity as well as during hibernation Bunting and Loevenhart (J. Phar., and found that the amount of CO, viii, 112). The tissues of the heart, in the blood of this animal is at all liver and the kidneys show considtimes greater than that of other mam- erable and serious changes. mals, but it increases progressively general impression obtained is that during hibernation and decreases the cells farthest removed from the when the animal wakes up. The dif- blood supply show the most proference between the amount of CO, in nounced lesions. In a previous comthe arterial and that of the venous munication by Lamson it was shown blood is much greater during hiberna- that an intravenous injection of epition. The same author (ibid., xli, nephrin in dogs and cats causes an 162) established in a later study that increase in the number of erythrothe anesthesia which has to be used cytes per unit volume of blood which during the activity of the animal does not occur if the hepatic artery In an indoes not influence the above stated was previously ligated. relations. It was found by Bert and vestigation by Lamson and Keath (J. others that in animals living at high Phar., viii, 247) it was established altitudes the oxygen-carrying power that when the hepatic artery is liof the blood is increased. This fact gated, intravenous injection of epiwas explained by Bert and others by nephrin causes a decrease in plasma the assumption that this greater oxy- volume without causing an increase in gen capacity at great altitudes is due the number of erythrocytes. It has to the decrease in the partial pressure been shown further that plasma volof oxygen in the atmosphere respired, ume and the number of erythrocytes which decrease causes an increase in per unit volume of blood may vary inthe erythrocytes and hemoglobin. dependently of one another.-Lamson Dallwig, Kolls and Loevenhart (J. P., (ibid., viii, 167) found that in rabxxxix, 77) established experimentally bits neither the intravenous injecthat indeed a decrease in the oxygen tion of epinephrin nor emotional stimtension of the respired air, obtained uli cause an increase in the red cell This indicates that by decreasing the oxygen concentra- of the blood. tion at atmospheric pressure, stimu- there is a difference between carnivlates the bone marrow and increases ora and herbivora with regard to the the erythrocytes and hemoglobin in regulation of the number of red cells the circulating blood of rabbits, white in the blood by the liver.-Anderson rats and dogs. The optimum oxygen and Neill pressure for increasing the oxygen capacity of the blood is apparently not far from 10 per cent. of an atmos

(M. R., xxxiii, 141) studied the blood picture of healthy rhesus monkeys, comparing it with the blood picture of man, and found that the red blood cells are slightly lower. Hemoglobin does more nearly approximate the normal values; white blood cells are also within normal limits, and basosphiles show relative preponderance over the polymorphonuclear leucocytes in monkey blood, contrary to the opposite ratio in adult human beings.

Howell (J. P., xl, 526) studied the structure of fibrin-gel. In blood of vertebrates the fibrin is deposited in

needles which form a close mesh work. Į turtle's heart. Schlomovitz and Chase (ibid., xli, 112) tried to attain a similar result as the last named authors by means of cooling and heating.