58 LIBBIE H. HYMAN. 



obtained numerous defective forms in Fundnlus by exposing the 

 eggs to low temperature at various periods after fertilization. 

 The eggs do not develop while in the refrigerator but if removed 

 even after a number of days to room temperature, some of them 

 will develop and numerous abnormalities are produced. Although 

 it is stated by Kellicott that every possible abnormality arises 

 under these conditions, yet perusal of his data show that the. 

 abnormalities are in fact limited to certain parts of the embryos. 

 These are : absent or defective head, absent or shortened tail, 

 various abnormalities of the brain and eyes, abnormalities of the 

 heart or circulatory system, abnormalities of wandering cells and 

 their products. 1 It is evident that the terata obtained by Kelli- 

 cott fall under the same heads as those obtained by Stockard 

 and others. Kellicott noted a marked susceptibility to low 

 temperature at the time when the germ ring is approaching the 

 equator. The low temperature used by Kellicott is more effective 

 than the chemical solutions employed by others since it greatly 

 inhibits the development without at the same time destroying the 

 blastoderm. It is important to note that when such greatly in- 

 hibited living masses are restored to room temperature sugges- 

 tions of organs develop such as " brain fragments, lenses, portions 

 of optic cups, groups of somites, masses of erythrocytes, rhythmic- 

 ally contractile cells arranged either as flat sheets or tubular 

 hearts, scattered pigment cells of the usual types, endothelial 

 cells over the surface of the yolk, fragments of notochordal 

 tissue." Kellicott did not notice the fact that these fragments 

 which develop from eggs retarded in early stages concern exactly 

 the same parts of the embryo in general as fail to develop when 

 the eggs are inhibited at later periods in their development. Loeb 

 ('15) obtained blind Funduhis embryos by means of potassium 

 cyanide solutions and low temperatures. One embryo is figured 

 by Loeb which possesses eyes and tail and nothing else. Werber 

 ('16) again obtained the same teratological types with butyric 

 acid and acetone-embryos with defective heads, including brain 

 (forebrain), mouth, and eyes, with approximated olfactory pits, 



i No observations were made by me on the wandering cells of the yolk sac. 

 It is reasonable to believe, however, that such cells are cells of high physio- 

 logical activity and hence highly susceptible to toxic agents. 



