344 Morgan. 



It appears from an examination of the analyses that indepen- 

 dently of the prematuration conditions, sperm lacking the character 

 M fertilizes with difficulty eggs lacking that same character 



On page 332 the results and analyses of the cross between rudi- 

 mentary miniature males and miniature females are given. The 

 analysis of the "Gametes of Fi" shows that the male producing 

 sperms rm may meet either of the two kinds of eggs, rMX or rmX; 

 the former contains M, the latter lacks M. The relative number of 

 the two kinds of males produced is a measure of repugnance when 

 both gametes lack the same factor. In this case there are 2,061 

 miniature males and 479 rudimentary-miniature males, — a ratio of 

 about ^.3 to I. 



Similarly, on page 335, another opportunity is presented to 

 examine the same influence. In this case there are 342 miniature 

 males to 98 rudimentary-miniature males, a ratio of 3.5 to i. Com- 

 bining these two we get a ratio of 4.17 to i. 



On page 335 a third opportunity is furnished, although a com- 

 plication is present (see below). As the analysis shows, equality 

 between rudimentary and miniature males is expected, except for 

 repugnance of certain gametes. In fact, there are four times as many 

 of one as of the other class, which again is the measure of repugnance, 

 except that in this case not only is M involved, but also the factor R. 

 Similarly, on page 330 a case like the last is found. Here the two 

 cross-over classes of males may also be utilized but only as compared 

 with each other. Miniature males are to rudimentary as 814 to 396, 

 or above 2 to i, and in the cross-over classes the long are to the 

 rudimentary-miniature as 240 to 74, or 3.1 to i. 



It will be seen that there is a considerable variation in the ratio 

 in the different combinations. How far these are due to deficiency 

 in numbers and how far to other conditions can not be stated. Con- 

 cerning the possibility of other conditions, I should like to call 

 attention to two points. When the rudimentary stock first appeared 

 it had a very low "viabihty". In F2 there were only 115 rudimentary 

 males to 4773 (calculated) normal males, when equality is expected. 

 I have, therefore, not utilized so far the cross on page 326. The stock 

 has improved since then, in the sense that the rudimentary males 

 are about as numerous as one fourth of the long winged males. The 

 cause of this improvement is obscure. 



My second point relates to the other factor, R, involved in this 

 cross. Do gametes lacking R also show repugnance? The analysis 



