1 82 Oscar Riddle 



worm. In Lampyris and Pyrophorus these substances are to be 

 found in the eggs and in every intervening stage up to the adult. 

 It is true that in this case the substances, in contrast to the Sudan 

 although not contrasting with the fat, do increase in amount at 

 given points in the cycle. But the general features of the tv^o 

 cases agree so closely that actual kinship of behavior seems certain. 



In conclusion, we may emphasize the fact that the transmis- 

 sion behavior of Sudan is the simplest of a simple class, and one 

 of which we can render mechanical explanation at practically every 

 point. It shows to us the simplest form of inheritance, if the 

 above analogies be granted. If the entrance of fat into the egg 

 and its persistence there is as stated; if the hereditary immuni- 

 ties are of similar origin; or if the "glow" susbtances mentioned 

 owe any considerable amount of their persistance to the type of 

 mechanics with which we have been dealing in the case of Sudan, 

 then this latter substance has proved of value in giving a view 

 detailed and clearcut, of the mechanism ot some phenomena which 

 have been generally considered inheritance phenomena. The 

 writer does not forget, however, the striking contrasts which these 

 cases present to the great bulk of developmental phenomena, and 

 which j-^^m to present quite a different magnitude of complexity. 

 He wishes to acknowledge his inability, for the present at least, to 

 state how the simpler cases here considered are to enter very 

 deeply into a solution of the more complex ones. 



It need hardly be pointed out, after our detailed account of the 

 action of Sudan, that these studies furnish no basis whatever for 

 the inheritance of acquired somatic characters. 



SUMMARY 



1 Sudan III fed to fowls and turtles is deposited in their grow- 

 ing ova. 



2 Ova and soma of birds and mammals take up this stain after 

 injection into the circulation or peritonial cavity. 



3 The dye molecule is closely united with the constituents of 

 the fat molecules and does not usually separate from them in the 

 body. 



4 Evidence is obtained indicating that the fatof certain regions 



