106 CAHNEGIE institution of WASHINGTON. 



Mutations in Poultry, by C. B. Davenport. 



While mutations hitherto observed in mammals (Castle) and 

 insects (Morgan) are usually due to the loss of a determiner, so that 

 the new condition is "recessive"to the former, in poultry the reverse 

 is frequently the case. Thus all modifications of the feet — extra 

 toes, syndactylism, absence of toe-nails — are dominant over the 

 typical condition. It is as though some extra determiner had entered 

 the mechanism and caused an irregularity of the developmental pro- 

 cesses in the feet. Also the absence of tail is a positive character; 

 there is an inhibitor to the development of this organ. One of the 

 most instructive instances of this sort of mutation is seen in the 

 abnormalities of feathering in poultry. Apparently all parts of the 

 outer covering of a bird had primitively the potentiality of producing 

 feathers. But secondarily this power has been lost in specific areas. 

 The shanks are devoid of feathers in many races, and when an indi- 

 vidual of any such race is mated with one of a shank-feathered race 

 the offspring are clear-shanked or nearly so; the inhibitor is derived 

 in the progeny from the clear-shanked parent, but the inhibition is not 

 perfect. I was able to get some bare-necked poultry and found, on 

 crossing them with the ordinary type, that half of the offspring have 

 naked necks. Here again the absence of feathers is due to a specific 

 inhibitor to the growth of feathers on the neck. Indeed, it is prob- 

 able that there are at least two inhibitors (for different areas of the 

 neck), since two types of "bare neck" occur. 



BIOCHEMICAL PROCESSES IN HEREDITY. 



The internal factors that direct the course of development are the 

 determiners; and it is by virtue of the fact that we can — through 

 crossing — combine determiners at will, that we are able to make new 

 and improved breeds. But between the determiners in the germ- 

 cells and the adult characters is a great gap and it is this gap that 

 chemical studies carried on here seek to fill. 



Chemistry of Ontogeny, hy R. A. Gortner. 



Dr. Ross A. Gortner has planned an extensive investigation of the 

 chemistry of ontogeny. For this work the adjacent State fish- 

 hatchery affords excellent facilities, for the use of which we are 

 indebted to the State Commissioners and to Mr. Charles H. Walters, 

 foreman. Trout eggs in five stages of development were used to 

 ascertain whether the chemical compounds that are present in the 

 egg enter the growing tissues in the form in which they are laid down 

 in the egg or whether there are synthetic changes taking place so 

 that the material which is present in the egg is used, not in its original 

 form, but in a modified condition. It seemed to Dr. Gortner that 

 synthetic action must take place, for otherwise we must think of 



