192 



COMPARATIVE PHYSIOLOGY 



different. By denoting M and F in terms of an arbitrary 

 system of numerical symbols Goldschmidt has elaborated 

 a system by which the appearance and degree of intersexuality 

 of his crosses between local races can be faithfully predicted. 



Race A 



T^ac€ B. 



Female 



F^ femaUs 



^walc 

 CM>F) 



Fig. 43. — Simplified representation of the results of Goldschmidt's 

 investigation of crossing in the gypsy moth Lymantria. The suffixes to 

 M and F denote the ** strengths " of the male and female factors. When 

 the sum of M is > F, the animal is male ; when < F, a female ; when = 

 F, intersexual. 



Many thousands of individuals have been employed in these 

 crosses. The accompanying scheme is a simplified representa- 

 tion by the author of Goldschmidt's essential ideas (Fig. 43). 



