The Sex Chromosomes. 261 
of analysis confine our attention to them. Here again I will 
consider primarily cases in which the male is digametic. 
In my third "Study (1906) I outlined two alternative 
possible interpretations of these cases. One of them assumed 
two kinds of sex-chromosomes, a female-determining and a male- 
determining, in accordance with the then prevailing view of 
Mendelian allelomorphism. The other assumed a purely quantitative 
relation of the sex-chromosomes, in respect to their degree of 
activity, or their total mass, or both. At that time I did not 
choose between these alternatives, but only analyzed the logical 
consequences of both. But already in my first preliminary paper 
(1905c) I expressed the opinion that ”the differences between 
eggs and spermatozoa is primarily due to differences of degree or 
intensity, rather than of kind, in the activity of the chromosome- 
groups in the two sexes“; and that ”the primary factor in the 
differentiation of the germ-cells (i. e., of the sexes) may be a 
matter of metabolism“. This view was strengthened as my work 
proceeded, and I gradually became convinced that the second 
or quantitative alternative was more in accordance with the facts 
(see 1909a, 1910 a). 
find any satisfactory eveidence that such is the case in any of the Hemiptera 
I have examined. 
Of more recent observations in this field I will refer only to 
Buchners discovery (1909) of an "accessory body‘ in the oogonia and 
oocytes of Gryllus, which he believes to be comparable to an accessory 
chromosome. This is supposed to invalidate my conclusions regarding the 
relation of this chromosome to sex in other forms. In the oogonial divisions 
this body passes to one pole like Giardinas chromatin-ring in Dytiscus, 
to which it is no doubt comparable. In the "bouquet-stage“ of the oocytes 
appears a condensed "accessory body“ that takes part in the general 
polarization of the chromosomes, as does the accessory chromosome of the 
male, and is for this reason forthwith identified by Buchner as an 
”"accessory chromosome“. The "accessory body“ of the oogonial divisions 
cannot be an accessory chromosome, or X-chromosome; for Gutherz 
(1910) has shown that the two X-chromosomes, characteristic of the female, 
are both present in the equatorial plates of the dividing oogonia, in 
addition to the ”accessory body“, which lies outside the equatorial plate. 
As to the ”accessory body‘‘ of the bouquet-stage, there is nothing to show 
whether this is or is not the X-chromosome nucleolus. In the latter case it 
should, of course, be a bivalent body. I will own to some admiration for 
the ingenuity that can discover in either case the slightest logical grounds 
for taking issue with my conclusions. 
