484 
Max Morse 
Historical. 
We shall review, briefly, tbe contributions which have tlius far 
been made to tbe study of the spermatogenesis of tbe species consi- 
dered in this paper. Leucophaea mcideriae Brun, and Redtenb. and 
Stylopyga orientalis (L.) have never beeu studied with respect to 
spermatogenesis, as far as tbe present writer can determine. Blatta 
germanica L. bas been used by la Valette St. George (’86) as 
material for tbe study of tbe derivation of tbe Spermatozoon, bis 
description begiuning with tbe spermatocyte. The latter work is of 
historical value only at the present time. 
Vom Rath (’91) used Blatta germanica as material for tbe study 
of amitosis, but for tbe present purpose, tbere is nothing of special 
interest involved. In the same species, Erlanger (’97) described tbe 
origin of tbe uebenkern and incidentally mentions the number of 
chromosomes in tbe primary spermatocyte as twelve, which is tbe 
number determined by later workers, Stevens and Wassilieff as 
well as by the present writer. Erlanger also figures tbe odd chro- 
mosome, but he does not designate it as such, wliile the contraction 
phase of the spireme is also represented. 
Farmer and Moore (’04), in a comparative review of tbe pbe- 
nomena of reduction in plants and animals, describe tbe behavior of 
the male sex cells of Periplaneta americana L. as typical for animals. 
In connectiou with this work, Moore, in colaboration with Robinson 
1/04) trace a bodv which they term the "nucleolus‘ ? throngh the sper- 
raatocvte stages and reach the following conclusions; 
. The beliaviour of the nucleolus in the different stages of 
spermatogenesis of P. americana is distinctlv interestiug on account 
of the wide ditference in its behaviour from that ascribed to similar 
structures by various authors in other animals. We find it, in fact, 
frequently described as an accessory chromosome, differing from the 
ordinary chromosomes both in structure and function. 
In the somatic cel 1 the nucleolus does not persist after the 
appearance of the spindle, but undergoes fragmentation, and is thrown 
out into the cytoplasm, where it undergoes degeneration. This pro- 
cess occurs in each successive somatic division, a nucleolus arising 
de novo, in each of the daughter nuclei resulting from each division. 
*) Stuiilmann ('86) has studied the oögenesis of this species. 
