DEPARTMENT OF EMBRYOLOGY. 103 



breadth analogous to that in human fetuses. After the fourth month 

 of intrauterine development the nostrils, which up to this time are cir- 

 cular in form, gradually become elongated, their longitudinal axes 

 converging forward in whites and occupying a transverse position in 

 negroes. In the former race it is the anterior portion of the nostril 

 that becomes distended as a result of the increase in the depth of the 

 nose, while in the negro the lateral part of the nostril distends as a 

 result of the great increase in nasal breadth. The variability in size 

 and form of the external nose was found to be very considerable in all 

 stages of fetal development. 



Before his return to Belgium, Professor 0. Van der Stricht completed 

 a study of the arrangement and structure of the sustentacular cells and 

 hair cells in the developing organ of Corti, and his excellent paper has 

 appeared during the past year. His observations were made on the 

 cat, dog, rabbit, and white rat, from the older fetal stages up to 12 days 

 after birth. By making oblique tangential sections through the organ 

 of Corti he was able to classify the histological arrangement of the ele- 

 ments of this structure and the mechanism of then- shifting during the 

 process of growth, and by a series of preparations stained to show the 

 mitochondrial structures in the supporting cells and hair cells he was 

 able to define the cytological nature of several structures which occur 

 in these cells. 



Since the last report a group of papers has been published dealing 

 with the results of the work in the Army Nem'o-surgical Laboratory 

 which was conducted during the war under the direction of Professor 

 L. H. Weed. These studies concern the central nervous system and 

 consist for the most part of investigations on the experimental produc- 

 tion of meningeal infections and localized traumatic abscesses of the 

 brain tissue. Of particular importance to the anatomist are the exper- 

 iments of Weed and McKibben, showing that intravenous injections of 

 hypotonic solutions are followed by a marked and sustained rise in the 

 pressure of the cerebrospinal fluid; on the other hand, intravenous in- 

 jections of hypertonic solutions cause an initial rise in the pressure, 

 followed at once by a marked fall, often below zero. These marked 

 changes in the pressure of the cerebrospinal fluid were subsequently 

 found to have a definite relation to the resultant volume of the brain. 

 Thus, following intravenous injections of strongly hypertonic solutions, 

 which lowered the pressure of the cerebrospinal fluid, there occurs a 

 marked shrinkage of the brain, so that when the skull is opened the 

 brain may be seen to have receded several millimeters from the inner 

 surface of the skull. Conversely, the brain bulk is appreciably in- 

 creased by intravenous injection of the hypotonic solutions which raise 

 the pressure, and when openings are made in the skull the brain pro- 

 trudes several millimeters through them. These changes are indepen- 

 dent of the volume of the fluid injected and are apparently due to the 



