410 
J. EiiOiNTE GATJBNBY. 
give the best results if it is used exclusively. Examining 
Meves’ beautiful plates one would be led to believe that the 
subject of the spermatogenesis of Lepidoptera, in so far as it 
touches upon the mitochondria and allied structures, has been 
exhausted. This is not the case. Meves has described for a 
number of species a remarkable dimorphism in the manner of 
formation of the sperms. Apart from the ordinary method, 
he describes how the chromosomes in the second maturation 
division fail to come together to form the spermatid nucleus 
but instead become at first vacuolated, and then finally recon- 
stitute themselves each like a small spermatid nucleus. The 
behaviour of the large mitochondrial body is fairly normal. 
He calls the abnormal spermatozoa “ apyrene Spermien ” and 
the normal “ eupyrene Spermien,” and shows that the sperm- 
bundles of “ apyrenes ” are several times shorter than the 
normal “ eupyrenes.” 
He finds such dimorphism in Pygaera bucepliala, 
Gastropacha rubi, Bombyx mori, and in Harpyia 
vinula. According to Meves, who has some weighty con- 
clusions to draw from the “ apyrene Spermien,” the latter are 
able solely to cause segmentation of the egg, only providing 
the centrosome, but not being able to carry paternal hereditary 
factors to the egg s which they fertilise, since theyhave no nucleus. 
Among others, the work of Dr. M. H. Cook may be men- 
tioned. In this paper (2) the chromosomes of the Lepidoptera 
have been examined successfully for the first time, and though 
no serious attempt was made to follow out the cytoplasmic 
inclusions, Dr. Cook’s work adds many facts of interest to 
our knowledge of the spermatogenesis of the Lepidoptera. 
I am unable to agree with some of this observer’s statements, 
especially concerning the spermatogonium, but otherwise we 
are generally in agreement. The remarkable bodies in Acro- 
nycta, sp., which Cook describes from a single pupa, would 
repay further observation ; I have difficulty in bringing one 
large accessory body, described as “ chromatin granule,” into 
line with any structures that I have been able to find in the 
species that I have studied. (However, see p. 446.) 
