SIDNEY I. KOENHAUSER 
conjugate laterallj^, remaining in contact merely at one end. 
They are not widely removed from the autosomes in their activi- 
ties and staining powers in the species. However, in other 
forms, such as Anisolahis, studied by the author, the Y-chromo- 
somes may exhibit entirely different staining reactions from the 
X-chromosome. It may be looked upon as degenerate from a 
cytological standpoint. 
Fig. 2. Mechanism of Sex-Determination in which Two Types of Ova are 
Produced 
The Z -chromosome is shown in solid black 
In many forms it is therefore not unlikely that, although there 
is no sex-determining mechanism visible to us with the aid of 
our best microscopes, nevertheless X and Y chromosomes exist, 
the Y-chromosomes being practically equal in size to the X- 
chromosomes and differing from them merely in the absence of 
specific genes. 
