The Chromosomes of Euschistiis variolarius, Euschistus serv'us etc. 495 
In Order to prove that the genital spot can be transinitted without the 
aid of the Y chromosome, it is necessary to show that it can be inherited 
directly through the female, and to prove that it can be transinitted with- 
out the aid of the X chromosome, it is necessary to show that it can be 
inherited directly from the male. Both these facts have been 
denionstrated by our breeding experiments with E. variolarius 
and E. servus. 
A full report of the facts is in print and the results illustrated with 
a complete set of phptographs, showing the exact appearance of the 
spot in the Fi and Fo males, as well as the results from a back cross, 
in which it is proved that the male can cUrectly transmit the spot. 
The bearing of these facts on the populär modern chromosome theo- 
ries was discussed in our preliminary report, from which we quote the 
following: 
“An analysis of the maturation divisions would seeni to support Castle’s 
S uggestion that the Y chromosome may be the bearer of exclusively male 
characters, for this chromosome is the only one that can be in both the 
so-called male-producing spermatozoa of each quartette of spermatids 
resulting from the two maturation divisions, assuming that these divi- 
sions occur as illustrated in the text figure. 
It would seem quite logical to conclude that if a character associated 
exclusively with the male sex can be inherited from thefather, the factors 
which produce it should be in the so-caUed male-producing Spermatozoon 
and if they are to be located in a given chromosome it must be the one 
and only chromosome that ex hypothesi can be present in all the so- 
called male-producing spermatozoa, othervise the character would not 
be a constant feature. 
If Castle’s Suggestion is correct, then all characters exclusively male 
can be inherited only through the father, as the Y chromosome is never 
in the female. If then Euschistus variolarius is fertihzed by Euschistus 
servus — a form which lacks the spot — none of the offspring should 
have it, neither the F^ nor the F2 generation. As a matter of fact, 
however, the spot of Euschistus variolarius is trans- 
mitted through the female — appearing in a slight degree in 
the males of the Fj generation and much more intensely in the 
F2 generation — some of the offspring of this generation having the 
genital spot quite as conspicuous as that of their E. variolarius ancestors”. 
“If we attempt to locate the spot factors in the X chromosomes, we 
cannot expect these factors to be transinitted through the male-pro- 
ducing Spermatozoon and therefore if an Fj female hybrid is fertihzed 
