274 FRANZ SCHRADER 
not separate, and only a protoplasmic bud is constricted off as a 
result. The next and last division, then, has the nature of an 
equation division. We may probably conclude also in T. vapor- 
ariorum that the last division is equational. By analogy with 
the Hymenoptera, it should be the division preceding this last 
which is the critical one, but, apparently, there is nothing of 
exceptional character in the division concerned, for, as far as can 
be determined, division plates here are exactly like those found 
in the spermatogonia. 
As in all other divisions, the most advantageous stage for 
counting the chromosomes is found just prior to the arrangement 
of the chromosomes into the equatorial plate. They are then 
irregularly distributed, but also less clumped, whereas they form 
a dense mass as soon as they have entered the plate. Eleven 
chromosomes can be made out. They are lengthened and iden- 
tical in appearance with those observed in the somatic cells. 
Preparatory phases of this division show no trace of tetrad for- 
mation. Finally, the telophases show what are, in all probabil- 
ity, equal masses of chromatin in each daughter cell, and there 
is certainly no abortive division at this time. As indicated 
above, it is to all intents and purposes a spermatogonial division. 
In spite of careful search, I could find no growth state pre- 
ceding the final division, although it seems improbable that such 
a phase should be lacking. The daughter cells resulting from 
this division receive apparently equal masses of chromatin. The 
number of chromosomes prior to division cannot be made out with 
certainty, but must be very close to eleven, while the number 
after the division cannot be estimated. This, then, is probably 
the ordinary equation division of maturation. 
It would appear, therefore, from the foregoing that there is in 
T. vaporariorum no abortive division, and that the first spermato- 
cyte division has been entirely suppressed. This conclusion is 
indicated also in another way. The spermatogonial as well as 
the spermatocyte cells of the various stages are always assembled 
in definite groups, and in most cases show a radiating arrangement 
around a common center which seems to indicate that they orig- 
inate from a single cell. All the cells of any one group are at 
