88 E. L. SHAFFER. 



fixation methods. With this in mind, the writer has sought with 

 most careful technical methods to obtain fixed material which 

 might not show these contraction figures; but without exception 

 cells in the contraction phase were always found in the definite 

 region of the testes mentioned above. It is quite true that 

 poorly fixed material shows an abundance of contraction figures, 

 but in these cases, as will be shown later, they are just as likely 

 to appear in other regions of the testes than in the very definite 

 location above mentioned. There is no doubt that even the 

 best fixation will tend to emphasize the contraction of the 

 chromatin just as it does in the case of the other cell structures, 

 but synezesis is unquestionably a normal process in the beetles 

 studied here. Whiting ('17) has advanced the idea that the 

 chromatic elements during synapsis are in an unstable condition 

 and that "any shock is likely to cause them to clump together." 

 It is questionable whether good fixation is much less of a " shock" 

 than indifferent fixation. It is conceivable that true synezesis 

 may not occur as a normal phase of the maturation possesses in 

 some animals (e.g., Orthoptera), but the fact that it has been 

 described by many workers using a variety of fixing methods 

 supports the fact that it is a normally occurring phase in some 

 cases. In any event it proves that the nuclear condition is 

 peculiar in cases of synezesis. 



Following the stage of synezesis, the chromatin threads are 

 released from the polarized bouquet in the form of thick ragged 

 looking pachytene threads (Fig. 21). Usually a longitudinal 

 split can be seen in the threads, which marks the point of synapsis 

 of the homologous threads. The chromomeres are imbedded in a 

 linin base, chromomeres of the same size lying opposite each 

 other and being connected with each other by fine linin threads. 

 In the later stages the threads become more widely separated 

 from each other (Fig. 23) assuming the diplotene form. In these 

 stages and in still later ones, the threads show a variety of twisting 

 about each other forming rings with and without crossed ends, 

 figures 8, double and even triple crossing-over of the threads. 

 In no case could a secondary split be seen. The strepsistene 

 threads continue to become more widely separated and it soon 

 becomes impossible to trace the individual threads (Fig. 22). 



