January 21, 1916] 



SCIENCE 



99 



ments are so far finished, but details about 

 them can not be published, because the records 

 are not available just now. But one point can 

 be stated in a general way. In my example, 

 the nun {Lymantria monacha), all gradations 

 are found between a white animal with the 

 characteristic zig-zag bands and a completely 

 black one. The breeding experiments show 

 that these intermediates are to be explained 

 by combinations of some, partly sex-linked, 

 factors for pigmentation. The comparison of 

 the wings shows that the pigmentation starts 

 from certain points of outlet and spreads 

 thence over the wing, gradually encroaching 

 upon the white scales. Obviously there corre- 

 sponds to every combination of factors, an 

 enzyme reaction, definite in quantity. Of 

 course, the same conclusion could already have 

 been drawn from Nilsson-Ehle's well-known 

 studies on oats. But the meaning of the re- 

 action is so much more evident in the insect 

 case. 



The other way which led to similar conclu- 

 sions in regard to the connection of hereditary 

 factors with the quantity of enzyme reaction 

 is quite an unexpected one. In some previous 

 papers I have published the results of experi- 

 ments in determination of sex in the gypsy 

 moth and a report upon their further progress 

 is now in press in the Proc. Nat. Acad. 8c. 

 The point which concerns us here is the fol- 

 lowing. We have found a series of races of 

 that moth, which differ in regard to the quan- 

 titative behavior of their sex-factors. We 

 could prove that in a cross between these 

 races the resulting sex with all the secondary 

 sex-characters depends upon the quantitative 

 relation of the male and female set of sex 

 factors. In the hybrids all kinds of combina- 

 tions of these two sets varying in their rela- 

 tive quantity, can be brought together. And 

 the result is that every single step between the 

 two sexes, for which I proposed the term inter- 

 sexes, may be produced. The external char- 

 acters of these animals now are determined in 

 the following way: the female factorial set 

 would produce entirely female characters, and 

 in the same way the male set male characters. 

 The real effect is a function of the arithmetical 



difference of these two. If this difference is 

 in favor of one or both above a certain quan- 

 tity, say / — my X or m — f > z, the pure 

 sex is produced. But if the difference is 

 beyond the constant minimum z and x, an in- 

 tersex is produced. And the quantity of inter- 

 sexuality increases proportionally to the de- 

 crease of the values / — m or m — /. The 

 effect of such a competition of two sets of 

 factors, both influencing the same characters 

 in different directions, is, of course, the same 

 as if only one factor of a variable quantitative 

 efficiency were present. And now we are able 

 to draw a parallel between the quantities of 

 the hereditary factor and the quantities of the 

 observed enzymatic reaction causing the 

 coloration of the wing. 



In the colors and markings of the wings of 

 these moths at least four factors or sets of 

 factors are involved, as is shown by loss-muta- 

 tions. The normal females have white wings 

 with transverse zig-zag bands, and, in addi- 

 tion, a crescent-shaped spot and a point near 

 it, resembling the Turkish emblem (crescent 

 and star). In the males the same markings are 

 present and also a diffuse color covering the 

 entire wing and varying from light gray to 

 almost black in different races. In a mutation, 

 which appeared some years ago in my cultures, 

 all ziz-zag bands, except the one near the edge 

 of the wing, disappeared. The mutation is not 

 sex-limited and independent of the general 

 color of the wing as is shown by breeding tests. 

 This general color is again subject to muta- 

 tions in the male; and there appeared another 

 mutation also in which the sex-linkage is 

 broken and the female wings are colored. The 

 following remarks apply only to the normal, 

 general wing-pigmentation, linked with the 

 male sex. 



It is known through the work of Federley 

 and others that this pigment flows out from 

 the wing-veins spreading over the entire wing. 

 And it might not be unsafe to say that it is 

 the oxydase which diffuses from the hemo- 

 lymph in the veins into the scales. If we now 

 study the different grades of intersexuality 

 produced in our experiments, we realize that 

 every step leading from a normal female 



