Germ Cells of Leptinotarsa Signaticollis. 199 



In the second division all of the chromosomes including the 

 bi-partite body divide. The latter probably divides longitudinally 

 so that two kinds of spermatids result, containing sixteen and 

 eighteen chromosomes respectively. 



The odd body is a basic-staining nucleolus that makes its 

 appearance in the synizesis stage when the other chromosomes 

 are in the form of a doubly segmented spireme whose halves may 

 be more or less separated. 



In the rest stage following, the nucleolus persists as a deeply 

 basic-staining bi-partite body while the remaining chromosomes 

 are represented by faintly staining clumps of matter distributed 

 on an irregular reticulum. 



The first step in the formation of the spireme of the ensuing 

 prophase consists in the appearance of two parallel strands of 

 linin extending from the nucleolus. These apparently represent 

 the framework of the spireme not only of this stage but of the 

 preceding synizesis. 



When the spireme appears, it is composed of a thickened double 

 thread whose halves are more or less closely applied to one another, 

 each of which contains sixteen segments. The nucleolus which is 

 attached to the nuclear membrane forms an additional member 

 in the series. 



After the spireme has broken up the sixteen bivalent chromo- 

 somes proper immediately shows signs of a second groove at right 

 angles to the first producing tetrad-like bodies. The bi-partite 

 chromatin nucleolus of the resting stage never shows such evi- 

 dence of a second division. 



In the ovocyte at a corresponding time there is a similar syni- 

 zesis stage and bi-partite chromatin nucleolus. Instead of pass- 

 ing directly into a rest stage as in the male, the chromatin knot 

 becomes disentangled producing the characteristic '' spireme" 

 stage which persists for quite a while. 



In L. decemlineata an odd body appears in the first spermatocyte 

 spindles, but in this case it is composed of two unequal parts. 

 Its behaviour in the maturation divisions is believed to be the 

 same as that described for the homologous body in signaticollis. 

 Synizesis stages of the ovocyte of decemlineata show a bi-partite 

 nucleolus also composed of unequal parts. 



JOURNAL or MORPHOLOGY. — VOL. 21, NO. 2. 



