STRUCTURE AND DIVISION OF TRICHOMONAS 133 



ize all of my slides which had been fixed with Flemming's fluid, 

 with the result that I detected this structure in T. batrachorum 

 and T. augusta from the leopard frog and in some slides of T. 

 muris fixed with weak Fleimning's. Later I found the same 

 structure in T. caviae in material fixed with weak Flemming's 

 and Flemming's without actic. The parabasal was most clearly 

 differentiated in the slides of T. muris fixed in weak Flemming. 

 Since in the weak Flemming the amount of osmic is reduced and 

 since, further, the parabasal appeared in slides fixed with 1 per 

 cent chromic acid, it would seem that the chromic acid is as 

 much if not more responsible for bringing out this structure than 

 is the osmic acid. Also, my experience does not parallel that of 

 Cutler ('18) in the case of formol, since none of my formol- 

 fixed preparations showed the structure. 



In the slides fixed with weak Flemming from mouse no. 24 

 a great majority of the flagellates showed the parabasal plainly, 

 while in a few it was difficult or impossible to make it out. In 

 the slides from mouse no. 29 fixed with 1 per cent chromic and 

 with Flemming's without acetic only a small percentage of the 

 flagellates exhibited the parabasal. There thus appear to be 

 individual variations with the same technique as well as differ- 

 ences due to differences in technique. Kuczynski ('14) found 

 the parabasal in only four out of more than fifty guinea-pigs 

 and in none of the mice, although over a hundred were examined. 



The above results point to the necessity of employing a variety 

 of methods of technique, since reliance upon a single method 

 might readily lead to erroneous conclusions. 



E. Encystment 



Encystment in Trichomonas has been much disputed, there 

 being few observations of a conclusive nature showing the exist- 

 ence of cysts. Wenyon ('07) called attention to the existence in 

 the faeces of the mouse of large numbers of rounded-up indi- 

 viduals which he stated could live for a week or more outside the 

 host if kept moist. Some others, which were much contracted 

 and rounded up, he thought w^ere encysted, and he figures such 

 a specimen in his figure 35, plate 11. I have seen many of the 



