552 Dobell, Some Eemarks upon the „Autogamy" of Bodo lacertae (Grassi). 



remains of the two axial rods of the Octomitus to which I then 

 attributed the cysts. 



Now all these results were obtained bj^ staining with iron- 

 haematoxylin, after sublimate-alcohol fixation — just as were Pro- 

 wazek's. On staining with more reliable nuclear stains (Dela- 

 field's haematoxylin, borax carmine), I was surprised to find that 

 only the „somatic nucleus" was coloured, the „chromidia" 

 and their derivatives remaining quite unstained. This fact 

 might perhaps also appear to be in harmony with Prowazek's 

 description. For although he does not say whether or not the 

 „chromidia" in the „autogamy-cysts" are coloured by any other 

 stains than iron-haematoxylin, he records that the „chromidium" ^) 

 in the free-living form („gametoid" individual) „mit den gebräuch- 

 lichen KernfarbstofPen, wie Grenacher's Hämatoxylin, IMkrokarmin 

 und Boraxkarmin . . . färbt sich sehr schlecht, nur mit EH kann 

 man ihn gut zur Darstellung bringen." In addition to their pecu- 

 liar reactions to nuclear stains, the „chromidia" appeared during 

 life to be much more highly refractive than chromatin usually is. 



The foregoing facts made me exceedingly sceptical of my ori- 

 ginal interpretation of the phenomena, and it was obvious that the 

 only way of deciding the matter lay in careful observation of the 

 living organisms. I therefore directed special attention to the living 

 cells, and observed the following phenomena. — For many hours 

 — sometimes for days — the cysts remained quite unchanged. The 

 first change which then occurred was quite unexpectedly a change 

 of shape. The cysts, which had previously been spherical, became 

 elongated (Fig. 4«). Meanwhile the „chromidia" appeared smaller. 

 Later, I found that the cyst wall vanished, and the cells assumed 

 an oval form (Fig. 4 h), the „chromidia" becoming very small and 

 finally dissolving in many cases. Still later, the „old nuclei", in- 

 stead of degenerating, divided, and the cells began to multiply by 

 budding (Fig. 5), and vacuoles made their appearance. Multipli- 

 cation proceeded very rapidly, so that large masses of cells were 

 soon formed. After growing in this manner for a few days (in 

 moist chambers), some of the cells began — as a rule — to form 

 long tube-like outgrowths (Fig. 6), probably as a result of the 

 anaerobic conditions. Many of these elongated forms subsequently 

 diveded into chains of long, brick-like cells (Fig. 7). In old cul- 

 tures, the refractive bodies („chromidia") again became conspicuous 

 in the cells. 



3) From the reactions and general behaviour of this structure, it is not at all 

 obvious why it should be called a „chromidiuni". There is no i^roof that it corre- 

 sponds with other structures usually so designated. Prowazek himself does not 

 seem clear about its real significance. It does not consist of chromatin, but of 

 „eine — sit venia verbo — plastinartige . . . Substanz (oder Substanzen) . . ." 



