STRUCTURE AND DEVELOPMENTAL RATE 165 



The periphery of the blastoderm in the eggs of the bird and 

 mammal or the germ-ring in a teleost's eggs is probably in some 

 sense comparable to the notched order of the budding leaf. At a 

 certain place along the germ-ring in the fish's egg a peculiarly 

 rapid cell multiplication begins and the embryonic shield with 

 the axis of the embryo buds away from this place. There is 

 already evidence for believing that more than the one place may 

 be capable of embryonic axis formation, and much is added to 

 such evidence by the experiments now to be presented. There 

 are many potential points around the germ-ring at which an 

 embryonic axis might arise. Here again, as in the plant, 

 when one bud or embryonic axis has arisen, it tends to suppress 

 the potential ability of other points to form an axis, and nor- 

 mally only one individual is developed from the egg. 



We are entirely unable to state the reasons why a certain 

 point along the germ-ring should form the bud and not another. 

 One can only imagine that this point has some peculiar advantage 

 of position which gives to it a higher power of oxidation and a 

 temporarily more rapid rate of cell proliferation than is possessed 

 by other points, just as the notch which is dipped below the 

 water surface possesses a budding advantage over the other 

 notches around the leaf. Can the advantage of position pos- 

 sessed by a particular point on the germ-ring be reduced so as to 

 equalize the budding tendency of several points and thus allow 

 them all to express their ability to form embryonic axes? Could 

 such a condition be brought about double embryos, twins, 

 triplets, etc., would be produced. 



The use of the word bud or budding in connection with double 

 embryo formations as employed by Patterson ('14) has been criti- 

 cised by Assheton, who suggests fission as the better word for 

 the process. Such a discussion seems devoid of value and I 

 employ the word bud to mean what is indicated above. 



