14 BULLETIN: MUSEUM OF COMPARATIVE ZOÖLOGY. 
metamorphosis of the head consists largely in an elongation. By Hen- 
neguy's method the neck-body is only rarely stained. This explains its 
absence in Figures 142-154. By Heidenhain's method it becomes in 
all spermatids a very conspicuous black spherical body (Plate V. 
Figs. 196-200). 
I pass now to a consideration of the results reached by other students 
of spermatogenesis in insects. 
Sabatier (90) has discussed in a short article the spermatogenesis of 
the Locustide. The conclusions to which he comes are rather startling. 
In regard to the metamorphosis of the spermatid, he says: “ Pres du 
noyau mais non à son contact immédiat apparait dans le protoplasme une 
vésicule sphérique . . . la vésicule protoplasmique." Sabatier main- 
tains that there is an almost total degeneration of the nucleus, but ad- 
mits that it gives rise to the “Kopfkappe”: “Cette derniere dérive 
donc du noyau et fournit un exemple remarquable de la dégénérescence 
ou altération du noyau de la cellule spermatique.” It is quite remark- 
able that the nucleus is able to form only the Kopfkappe when, presto, 
* cette vesicule devenue fusiforme et vivement colorable constitue ce que 
Pon considere comme la tête du spermatozoïde.” 
I have never seen any such nuclear degeneration, nor any extra- 
nuclear vesicle of such paramount importance. The head of the Calop- 
tenus spermatozoón arises from the six chromosomes inherited by each 
spermatid. 
Blochmann ('87) describes the formation of the polar bodies in Blatta 
germanica. 
The work of vom Rath ('91* and '92) on the spermatogenesis of 
Gryllotalpa must receive special notice. My account of the spermato- 
genesis of Caloptenus confirms a large part of vom Rath's results, but 
differs from his in several points, and suggests another interpretation 
of the last two divisions. What these differences are will soon be 
apparent. 
Vom Rath (93) has already called attention to the many groups 
of animals in whose spermatogenesis or oógenesis ring formation and 
Vierergruppen have been observed by different authors; but with one 
exception (Flemming, '87) he mentions those authors only who have 
noticed and remarked about these chromatic figures. It may seem ven- 
turesome, but I wish to suggest the same interpretation for the figures 
of various authors who either had no definite idea of Vierergruppen, or 
considered the conditions exhibiting them abnormal (Flemming, '87), 
