September 7, 1906.] 



SCIENCE. 



295 



fuse together to give rise to the male or 

 female eggs suggests that the position of 

 the eggs in the ovary and their relative 

 isolation or crowding may here be the sex- 

 determining factor. 



Glycogen in the Nervous Tissue of Embryo 

 Mammals, with Demonstration: Simon 

 H. Gage, Cornell University. 

 From the first discovery of glycogen in 

 animal tissues by Claude Bernard in the 

 fifties until the present time, all investiga- 

 tors assert that glycogen is not present in 

 nervous tissue at any stage of development 

 or during any state of activity. In the 

 summer of 1904 while at the Bermuda 

 Biological Station Amphioxus material 

 was fixed in absolute alcohol for the de- 

 termination of glycogen. Abundant 

 glycogen was found in the large nerve cells 

 of the central nervous system in both 

 Amphioxus and Asymmetron. From this 

 discovery it was believed that glycogen 

 would probably be found in the nervous 

 tissues of mammals if they were taken at 

 the right time. A series of pig embryos 

 from 7 to 70 nun. were sectioned and plenti- 

 ful glycogen was found in the cells of the 

 dorsal ganglia in embryos from 7 to 20 mm. 

 In the 20 mm. embryo glycogen was also 

 present in the developing nerve trunks, 

 and in older embryos it nearly or quite dis- 

 appeared from the ganglion cells but be- 

 came exceedingly abundant in the nerve 

 trunks. These facts point to the conclu- 

 sion that at some period in the growth of 

 nervous tissue glycogen plays as important 

 a part as in the other tissues of the body. 



The Notochord of the Head in Human 

 Embryos of the Third to the Twelfth 

 Week, and Comparisons with Other 

 Vertebrates: Susanna Phelps Gage, 

 Ithaca, N. Y. 

 In the Cornell collection are many 



sagittal series which are especially favor- 



able for the study of a mesal organ like the 

 notochord. In ahuman specimen of sixty 

 days the relations of the notochord to the 

 cartilaginous base of the skull and the 

 epithelium of the mouth are clear. On 

 emerging from the axis, it forms a knotted 

 protuberance dorsal of the base of the 

 skull, passes diagonally through it to a 

 pocket from the roof of the mouth, thence 

 cephalad to come in contact with two other 

 mouth pockets, thence diagonally dorsal 

 through the base of the skull, again form- 

 ing a knot and turning sharply ventrad, 

 ending near the hypophysis but within the 

 cartilage. 



The same relations exist in a specimen 

 of forty-eight days in which the base of 

 the skull is not as far from the roof of the 

 mouth and the excursion of the notochord 

 is not so far ventrad. 



At thirty-six days the condensed meso- 

 derm foreshadows the skull, and the same 

 general relations occur, the ventral excur- 

 sion of the notochord being very limited 

 and touching the straight roof of the mouth 

 in three or four loops. 



At twenty-eight and twenty-one days the 

 notochord lies directly in contact with the 

 epithelium of the roof of the mouth, thus 

 showing the beginning of the history. 

 Transections verify the above observations. 



The comparative study of pig, sheep, 

 calf, mouse, eat, chick, amblystoma, frog, 

 shark and lamprey shows that the noto- 

 chord after the earliest stages is usually 

 completely separated from the roof of the 

 mouth, being included in the more con- 

 densed tissue forming the skull and taking 

 a straight course. In the pig, however, 

 about twenty per cent, were similar to man, 

 being in contact with mouth pockets. 



In the calf, contrary to the observation 

 of Froriep, the specimen examinM showed 

 the usual straight form. 



The cephalic tip of the notochord in the 



