424 MALL. [VoL. XII. 
two embryos of this stage, Nos. Iand XV, which had been taken 
out of the chorion and torn from the umbilical vesicle, and both 
of them are straight like Kollman’s embryo Bulle and His’s? 
embryo L. It is difficult to conceive how my embryo XII 
could possibly be torn out of its membranes without straight- 
ening it. Weneed only 
recall our experience in 
hardening embryos of 
lower animals to be re- 
minded how easily a 
curved embryo is 
straightened when it is 
handled the least bit 
roughly before: itis 
hardened. 
His,.an/ his) (eneat 
monograph on human 
Gar AA ie embryos, emphasizes a 
curve in the back of the 
embryo just the reverse 
of the one given in Fig. 
21. Irefer'to-embryos 
sch. BB.) and) Wezas 
well as to Minot’s em- 
bryo) 195.7). he: sfact 
that this inverted bend 
Jo Goce ousrm nin sauae (cts a Tun con 
coelom ; «7, umbilical vesicle; ad, allantois; A, — stant (His’s Ri., | for 
medullary plate; 7 c, neurenteric canal. zi i 
instance), and that it 
occurs at the time when any tension upon the umbilical ves- 
icle could produce it, makes me believe that it is an artifact. 
This view was suggested to me a number of years ago, when I 
was removing young dogs’ embryos from the uterus, and unwit- 
tingly distorted a number of them in this very way before they 
were hardened. The middle of the back is the weakest part 
of the embryo’s body, and the umbilical vesicle is attached to 

1 His: Anat. mensch. Embryonen, Plate VI. 
2 Minot: Human Embryology, New York, Fig. 169. 
