SPERMATOGENESIS IN ASILUS SERICEUS 173 
One author (Arnold, '08) has described in Hydrophilus piceus 
(Coleoptera) a precocious reduction of the chromosomes at the 
beginning of the growth period not unhke that found in Asilus. 
But the brevity of his description together with the fact that no 
other observer (Stevens, Vom Rath, '92, Goldsmith, etc.) has 
noted such a phenomenon in this or other Coleoptera makes it 
seem probable that Arnold is mistaken in his interpretation. 
It appears, then, that although a superficial similarity exists 
between the early growth stages of Asilus and those of various 
other animals, the divergence between the double (bivalent) 
chromatic bodies on the one hand and the single ones on the 
other separates the representative of the Diptera from all the 
other forms.'' 
If we turn to the plants, however, we find a different situation. 
Here, although the evidence is not as clear as might be desired, 
some species appear to exhibit a paired association of 'prochromo- 
somes,' in the early growth period immediately after the last 
diploid telophase, somewhat like that found in Asilus. Overton 
('05, '09), for instance, records such an association in Thalictrum, 
Calycanthus, Campanula, and Helleborus. In these the last 
diploid division is followed by a resting-stage network in which 
definite chromatic bodies (prochromosomes) are scattered about. 
These are diploid in number, but often, or usually, lie in paired 
association. Their shape and degree of condensation differ in 
different cases, but their paired association seems to be fairly 
constant. In these plants the association may persist from the 
last 'premiotic' anaphase through the growth period and up to 
the metaphase of the reduction division, although Overton does 
not commit himself as to the behavior in the telophase and 
earliest stage of the growth period, as indicated by the following: 
^ The earlier literature of spermatogenesis contains numerous references to 
possible or supposed precocious pairing in the last spermatogonial telophases. 
For instance, Montgomery, '00, page 297, on Peripatus, notes a few such 'excep- 
tional' cases; Blackman, '03, '10, page 141, on Scolopendra, describes a pre- 
cocious telosynapsis; Stevens, '03, on Sagitta, suspects an early pairing, and 
Downing, '05, on Hydra, makes a similar suggestion. Other and more recent 
examples could be cited also, but in no case have we been able to find clear-cut 
evidence of such an association as is exhibited by Asilus. 
