No. I.] SPERMATOGENESIS OF BATRACHOSEPS. 75 



cells in this species of Helix, I can, of course, not express 

 myself positively, but merely wish to call attention to the simi- 

 larity and to the probable explanation. 



In his review of ZclltJieilimg iox 1897, Fr. Meves expresses 

 his opinion that the ring-shaped nuclei described by Moore in 

 the testes of the elasmobranchs are simply artefacts caused by 

 reagents. In this I cannot agree with Meves, but must, on 

 the other hand, express it as my decided opinion that the ring 

 and umbrella stages represent actual phases of chromosomic 

 evolution, equal in importance to any of the other mitotic 

 figures. 



The object of the ring and umbrella stages is, according to 

 my idea, twofold. First, to allow the chromoplasts to rearrange 

 themselves, that is, to proceed from the ends of the chromo- 

 somes of the auxocyte (where they are located at the time the 

 chromosomes move apart) to the angle of the two prongs of 

 the chromosomes, where they must be in the beginning of the 

 new mitosis of the spermatocyte. Another object is to allow 

 the chromioles an opportunity to divide and to be properly 

 nourished during this division. It may also be possible that a 

 rearrangement of the chromioles takes place, though we have 

 no observations that would indicate that such is the case. I 

 have some reason to think that such ring and umbrella stages 

 are much more common than we suppose, and that they have 

 often been allowed to remain undescribed on account of the 

 belief of the investigator that they were mere artificial prod- 

 ucts of the fixatives. 



That the first object of the umbrella stage, as stated above, 

 is not the only one is evident from the fact that we also find 

 an umbrella stage in the spermatocyte. As in this cell the 

 chromosomes have from the beginning, or from the time they 

 reappear, their chromoplasts situated at the angle where the 

 arms of the chromosomes meet, it is evident that the same 

 rearrangement of the chromoplasts cannot be an object in 

 this class of cell. It may, however, be possible that the chro- 

 moplast must occupy yet another position in the spermatid, 

 and that this is also accomplished in the umbrella stage of the 

 spermatocyte. In the spermatid the chromoplasts appear to 



