Nineteenth Meeting. 



ScJiermerhorn Hall, Columbia University. December ip, 1906. 

 President Flexner in the Chair. 



17 (160) 



An experiment on the localization problem in the egg of 

 Cerebratulus. 



By NAOHIDE YATSU. 



[From the Zoological Laboratory of Columbia University^ 

 In the egg of Cerebratulus marginaius Zeleny found, in separat- 

 ing at the 8-cell stage the upper animal blastomeres from the lower 

 vegetative ones, that the third cleavage plane cuts off the basis of 

 entoderm from that of ectoderm. I repeated the same experiment 

 on the egg of Cerebratulus lacteus and found that the condition is 

 somewhat different. In this form the third cleavage does not 

 always separate the entodermic stuff from the ectodermic, so that 

 the embryo from the animal-half sometimes invaginates and some- 

 times does not. But in shifting the third cleavage plane to the 

 equator by compressing the egg immediately after the first divi- 

 sion (in doing this, the second cleavage is suppressed until pres- 

 sure is relieved, the third cleavage of the normal egg appearing 

 next to the first) and in separating the animal-half from the vegeta- 

 tive, the former always gave rise to the embryos without gut, 

 anenterons. From this it may be concluded that in the egg of 

 Cerebratulus lacteus, a little before or at the time of the third 

 cleavage, the entodermic basis extends farther above than that of 

 Cerebratulus marginatus. 



18 (161) 



Experiments upon the total metabolism of iron and 

 calcium in man. 



By H. 0. SHERMAN. 



[From the Havemeyer Laboratory, Columbia University^ 



Each of the experiments was of three days duration and the 

 same healthy man served as subject throughout. On a diet of 



(21) 



