ORIGIN OF MONSTERS 499 



blance witli fish embryos of a corresponding age, and goes all 

 the way down to such forms where such gross-morphological 

 similarity is entirely obhterated (figs. 24 to 34). 



Thus embryos may be found with rudimentary eyes in which 

 the anterior part of the body has widened out to a very striking 

 degree, with club-fins and a club-tail. Not uncommon is the 

 occurrence of greatl}^ elongated and misshapen embryos often 

 with waisthke constrictions (figs. 28 and 29), with rudimentary 

 fins or (sometimes) dislocated fins (figs. 29 and 31). This group 

 would comprise also some remarkably misshapen and dwarfed 

 embryos (figs. 25, 26, 27 and 32) and finally embryos whose form 

 would almost seem to suggest a similarit}^ to some invertebrate 

 animals (figs. 33 and 34). 



3. M era plastic embryos 



Very great numbers of eggs were found both in butyric acid 

 and acetone experiments in which parts of the bodies have 

 developed, while the rest of the germ has apparently suffered 

 destruction ('Meroplasts'-Roux, I. c). 



In such meroplastic embryos the same wide range of variation 

 obtains in the degree of defect, as in all other monsters recorded 

 above. Common to nearly all of them, howe^'er, is that, usually 

 it is the anterior part of the body that develops, ^^']lile the pos- 

 terior part is lacking. The variations in defect concern the 

 organs of the meroplasts as well, as the (luantity of what has 

 developed. A glance at figures 35 and 30 shows that the eyes 

 may be variously defective and the same obtains for the ear- 

 ^'esicles. Likewise the shape and size of the meroplasts are yeiy 

 inconstant. The meroplastic embryo may correspond to more 

 than the anterior half of an embryo or be just about half of the 

 embryo's body. The latter ones recall the hemiembryos which 

 Roux ('95) and later other investigators have obtained by injur- 

 ing one of the first two blastomeres of the frog's egg. 



Finally the meroplasts should be mentioned which are less 

 than half of the body (figs. 37 to 41). Not infrequently all that 

 can be seen to have develo]ied is a more or less malformed head, 

 recognized only by the presence of a I'udimciitary eye ffig. 37). 



THE JOLRXAL OI' KXI'KKIM KNT AI. /.(xiLOdY, VOr, 21, NO. 4 



