DEPARTMENT OF EMBRYOLOGY. 119 



rounding the labyrinth on the one hand and the transverse sinus on the 

 other. It may be a single or a multiple channel. Through it are 

 drained the plexus of the endolymphatic sac and some of the dural 

 veins of the immediate neighborhood. 



A communication concerning the development of the tissue-spaces 

 around the membranous labyrinth has been pubhshed by Dr. Streeter. 

 The largest of these are the scala vestibuli and the scala tympani. 

 Their development was traced in human embryos from the earhest 

 stage up to the adult type. The important fact was estabhshed that 

 in their formation they follow a definite morphological plan. They 

 spread from two foci, the larger one beginning as a rounded sac lying 

 opposite the foot-plate of the stapes and lateral to the sacculus, from 

 which point it subsequently spreads upward over the utricle and also 

 downward along the apical side of the cochlear duct to form the scala 

 vestibuU. The other focus is near the fenestra cochleae, whence it 

 spreads along the basal side of the cochlear duct to form the scala 

 tympani. These foci can be definitely outlined in fetuses 50 mm. 

 long. In 85 mm. fetuses the two scalse extend spirally downward along 

 the cochlear duct to a point three-fourths of its last turn from the tips 

 of the duct; they do not communicate with each other. In fetuses of 

 130 mm. they extend to the tip of the cochlear duct and open into each 

 other, thereby forming the helicotrema. 



Although the spaces around the membranous labyrinth resemble in 

 their histogenesis the formation of the subarachnoid spaces, they can 

 not be regarded as an extension of these, because their development 

 is in loco and independent of them. In the latest stage examined 

 (130 nmi. crown-rump length) the communication ^dth the sub- 

 arachnoid spaces has not yet been estabhshed. 



Several papers have been pubhshed during the year on the anatomy 

 and development of the nervous system. They include a morpho- 

 logical study of the inferior olivary nucleus in the human fetus; the 

 vestibular and optic mechanisms and their relation to the falhng 

 reflex of cats; a chnical study of the Gasserian ganghon; and a study of 

 the development of the pharyngeal pouches in the turtle, in which 

 special attention is devoted to the neural placodes. 



Professor George B. Jenkins has contributed a study on the anatomy 

 of the inferior ohvary nucleus of the brain, which forms a continuation 

 of the studies on this subject previously pubhshed from this laboratorj^ 

 Dr. Jenkins has approached the subject from the embryological side, 

 and gives a morphological description based on reconstructions of the 

 ohve and its accessory nuclei in a human fetus, 280 mm. crown-rump 

 length. His study also takes into consideration other fetuses belong- 

 ing to the Carnegie Collection, in which the olive was studied but not 

 reconstructed. 



Doctors H. R. MuUer and Lewis H. Weed have pubhshed an experi- 

 mental study on the rotational reflex by which cats are able to turn 



