MALE CELLS OF RHOMALEUM MICROPTERUM BEAUV. 3 



technique. Ample data for the purposes of this paper were 

 secured, however, since cells can be secured at any desired stage 

 without watching any particular cell for any great length of time. 



OBSERVATIONS. 



However we may interpret the behavior of the chromosomes, 

 Rhomaleum corresponds in all essentials with the account of 

 orthopteran spermatogenesis given by Davis ('08) for Dissosteira, 

 with the Hippiscus type of the Acrididae as described by McClung 

 ('14) and with Phrynotettix (Wenrich, '16). A connected account 

 of the stages through which the chromosomes of Rhomaleum 

 pass during the growth period would therefore correspond in 

 most respects with that given by Davis. 



In the spermatogonia the cytoplasm in fixed material is com- 

 paratively clear except for a minute fibrillar network. In addi- 

 tion several minute but darkly staining granules can usually be 

 seen scattered about the cytoplasm. Mitochondria are appar- 

 ently never visible in the spermatogonia even when the material 

 is fixed in the modified Flemming and stained with the so-called 

 mitochondrial stains. In living material however the cytoplasm 

 shows no fibrillar network, but the mitochondria appear ir- 

 regularly scattered about the cytoplasm or more often in a. 

 fairly dense mass close to the nuclear wall. In the resting stages- 

 in Rhomaleum they are very delicate granules, staining brilliantly 

 with janus green, and show very little tendency toward any 

 thread-like arrangement. No dividing primary spermatogonial 

 cell was observed. In the resting stages of the secondary 

 spermatogonia the mitochondria apparently have a tendency to 

 be less scattered and more densely crowded next to the nuclear 

 wall (Fig. i). In dividing secondary spermatogonial cells the 

 mass of granules is arranged in irregular rows about the spindle, 

 and fairly evenly divided without assuming any definite thread- 

 like form. The granules visible in the fixed material can also 

 be seen in the living cells. They are usually five or six in number, 

 and do not stain with janus green. After being treated with 

 neutral red for about an hour, however, they appear faintly pink. 

 The number is often as large in the secondary as in the primary 

 spermatogonia, and this gives some reason for supposing that 



