Dobell, Some Remarks upon the „Autogamy" of Bodo lacertae (Grassi). 549 



place as follows: A number of Bodos become united at their po- 

 sterior ends, forming a kind of „Agglutinationsstern". Each animal 

 later undergoes a shortening and finally rounds itself off and forms 

 a delicate cyst membrane. The autogamy-cysts thus occur together 

 in little heaps. Inside each cyst an autogamy is now enacted. At 

 first the nucleus increases in size. Then small bladder-like chro- 

 midia are extruded from it into the cytoplasm. Their maximal 

 number is 8. They soon come together and fuse, forming the 

 sexual nucleus. A stage is thus reached in which the cyst contains 

 two nuclei — the pale (poor in chromatin) somatic nucleus, and 

 the darker (richer in chromatin) sexual nucleus. The sexual nucleus 

 now divides by amitosis; each daughter nucleus again dividing 

 similarly, so that four nuclei are formed. Of these, two divide 

 once more, so that six small nuclei come to lie round the somatic 

 nucleus. Four of these are reduction nuclei and degenerate: the 

 other two are the gamete-nuclei, which increase in size, approach 

 one another, and fuse. Thus once more the cyst contains two 

 nuclei — the old somatic nucleus and the new synkaryon, formed 

 by the fusion of the gamete nuclei. In this stage the cyst remains 

 for some time: then finally the new nucleus increases in size and 

 forms a new karysome, while the old nucleus degenerates^). A 

 thick cyst membrane is formed, and we thus reach the final stage 

 — the yellow, durable cyst. 



Whilst I was working at the life-histories of the protists in 

 the gut of the frog, I' came across some small cysts which bore a 

 very close resemblance to those described by Prowazek as be- 

 longing to Bodo lacertae. It appeared to me that they were the 

 cysts of some small protozoon which went through an autogamic 

 process almost identical with that of Bodo. For some time I ima- 

 gined that the cysts belonged to the Octomitus in the frog's gut, 

 but I was unable to confirm, this opinion. I was able to find 

 practically every stage described by Prowazek (See text-fig. 1, a — ^2^)- 



First of all, there were cysts containing a single large nucleus, 

 usually with a conspicuous karyosome («). Then there w^ere stages 

 showing the bladderlike „chromidia" emerging from the nucleus 

 (/;, c). And a very large number of the cells had an appearance 

 like that shown in d, where the „old, somatic nucleus" and the 

 „chromidia" are completely separate. I also found stages in which 



2) Prowazek's description is not clear on this point. He says that the „old 

 nucleus" decreases in size, becomes dense, uniformly darkly-staining with iron-haema- 

 toxylin, and sometimes shows a central pale space. He then describes and figures 

 (Fig. 81, plate III) how the two nuclei may come together. No figure of a uni- 

 nucleate cyst in given, nor is it definitely stated that the „somatic nucleus" com- 

 pletely disappears — though in one place it is referred to as" den alten der De- 

 generation anheimfallenden Kern" (p. 27). 



