24 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
According to my interpretation of the Vierergruppen in Calopte- 
nus, the formula would be {eat . Both the divisions following the 
formation of a Vierergruppe would therefore be reductions, and it would 
be quite immaterial whether the first di- 
2. vision gave rise to two cells « b and cd, 
or to the two cells ac and bd. In Calop- 
tenus the rings may be placed upon the 
a D spindle equator in either of the two posi- 
2 | ^ tions represented in Diagrams 1 and 2, 
" This offers, perhaps, an explanation and 
reconciliation of the contradictory views 
of Henking, Hertwig, Häcker, and others. 
As has been said, Henking holds that the 
first division is a reduction division, and 
the second an equation division, while most authors make the first an 
equation, and the second a reduction division. Henking (791) did not, 
in his Pyrrhocoris paper, recognize the existence of Vierergruppen 
as a regular stage in: maturation; but I feel justified by his Figure 20 
in believing that they were really present in Pyrrhocoris, just as in 
Gryllotalpa, Caloptenus, etc. Now, supposing the proper formula for 
the Vierergruppen to be 15 f , why might it not happen in dif- 
ferent nuclei, or in different chromatic groups of the same nucleus, that 
a 
1 
one group should divide thus, £, and another thus, 9 Henkin 
group 575 > blb d 
must assume that all the groups are arranged on the spindle so as to 
separate the non-identical idants by the first division. Häcker says: 
“In der zweiten Richtungstheilung erfolgt dann die definitive Trennung 
der nichtidentischen Idantenpaare." 
The following diagrams may illustrate these positions : — 
I IT. III 
a a a b de awe D 
u e e o eo © © 
dd ore DU ooa mi š d e SEA A iS obe Er 
b b a b DR Td bt 
Diagram T. illustrates Henking’s view of the first division interpreted 
according to the scheme of the Vierergruppen. All the groups would 
thus suffer reduction division. 
