458 C. OLIFFOED DOBFLL. 



isms, tliis conclusion might have appeared to some extent 

 justified. After fixing- and staining some of the cells, a large 

 nucleus was seen to be present. It therefore appeai'ed to me 

 at the time that I had discovered a new Bacterium which 

 possessed a well-marked nucleus, and hence belonged to the 

 group of organisms of which B. gammari is the type. 



Stained examples of this organism from the boa are shown 

 in figs. 137, 138, 140, 141 and 144 (PI. 19) and in fig. 135 

 (PI. 18). Owing to the watery nature of the rectal contents, 

 and to the large amount of grit present, it was found very 

 difficult to obtain good wet-film preparations. Most of my 

 stained preparations were therefore made by allowing some 

 of tlie fluid containing the organisms to dry upon a slide ;^ 

 then fixing the dried film in absolute alcohol; and finally 

 staining with Griemsa's stain. Asa cj^tological method this 

 is of course unsatisfactory; but the results obtained were, in 

 the main, good enough for arriving at conclusions regarding 

 the general structure of tlie cells. In most cases the nucleus 

 had undergone a certain amount of fragmentation — owing to 

 drying — but it frequently showed its vesicular structure quite 

 clearly. 



In fig. 137 a number of small individuals are depicted — 

 each showing a distinct nucleus. Fig. 138 shows two larger 

 individuals, of the characteristic Bacterium form, Avitli 

 rounded ends. Fig- 141 show^s a similar organism, but with 

 ends of a squarer form. The nucleus is iu all cases unmistak- 

 able. In fig. 140 a chain consisting of four organisms of a 

 more or less bent form is seen. The nuclei are all somewhat 

 broken up through drying. Fig. 144 shows another chain 

 of four individuals, of smaller size, and each containing a vesi- 

 cular nucleus. Forms intermediate in size between these 

 small forms and the larger forms occui-, so that there is no 

 reason for regarding them as different species. I propose to 

 call all the individuals wliich have the rod-form characteristic 



' At the time when these oljservations were made (1900) I had not 

 discovered the osmic acid drop method of fixation which has since 

 proved so useful. 



