ON THE DOMESTIC FOWL. 249 



characters of the progeny will be considered, and as before primary 

 attention will be given to such characters as admit of quantitative 

 expression. 



1. Plan of Matings in 191 5. — The alcoholized birds and the un- 

 treated controls were mated early in February, 191 5. Eggs were 

 saved for incubation from these matings from about February 15. 



The general plan of the matings in 19 15 was to breed a treated 

 male of each of the three classes, ethyl, methyl and ether, with (a) 

 untreated control females, and (b) with treated females of his own 

 class {i. e., ethyl ^ X ethyl $, methyl ^ X methyl $, ether S X ether 

 5). In addition to these matings an untreated control male was 

 mated with (a) untreated control females, (&) ethyl females, (c) 

 methyl females, and ((/) ether females. 



All of the matings were of the type Black Hamburg ^ X Barred 

 Plymouth Rock $. There were produced 234 chicks from matings 

 wherein one or both parents were treated. 



2. Germinal Dosage Index. — In the present investigation the fol- 

 lowing reasoning has been used in devising a numerical expression 

 of the dosage, so far as concerns the progeny. Two germ cells, a 

 sperm and an ovum, unite to form the zygote of each progeny indi- 

 vidual. It is proposed to designate as the " total germ dosage index " 

 the total number of days during which the two gametes making the 

 offspring zygote have been exposed to alcoholic influence while so- 

 journing in the body of the treated individuals. Such a germ dosage 

 index could, of course, be calculated for each individual progeny 

 chick born. It seems, however, more desirable for present purposes 

 to combine the figures for each mating, and take the sum of the 

 number of days from the beginning of treatment of the male parent 

 to the average date of hatching of the progeny, plus the number of 

 days from the beginning of treatment of the female parent to the 

 average date of hatching of the progeny as the germ dosage index 

 for that mating. This can be expressed in a formula as follows : 



Total germ dosage index in days=^(Mh — A(^)-j-(]\In — A^) 

 where 



il/ft =Mean date of hatching of progeny. 



A(^ = Date when treatment of (^ parent began. 



A2 ^Date when treatment of $ parent began. 



