198 JOTTINGS FROM SYDNEY UNIVERSITY BIOLOGICAL LABORATORY, 



contraction. When in a quiescent condition they had the form 

 represented in figure 2 — approximately cylindrical, sharply pointed 

 at one — the anterior — end, less sharply at the other ; in length 

 they were "005 mm. and in greatest breadth -002 mm. In many 

 cases a series of movements, successive phases in which are 

 represented in figures 3 to 7, followed one another in rapid suc- 

 cession. A glance at the figures will show that these movements 

 are just the movements which are calculated to force a soft 

 contractile body through such an obstacle as the protoplasmic 

 network of a cell would present,- — a narrow process thrust forward 

 to force a passage, a thickening formed at the end of this process, 

 and the main mass of the body drawn forward into this ; then a 

 fresh process thrust out in the same direction, and so on. At 

 the same time, especially when the animal was still confined 

 within a cell, there were frequent active twisting movements. 

 In the interior of the mobile protoplasm of the parasite were a 

 good many small rounded and rod-shaped particles of a greenish 

 colour. These were most abundant about the middle, almost 

 completely absent at the anterior extremity. A little behind the 

 middle was a rounded space free from these green particles ; this 

 proved, when staining agents were used, to be a rounded nucleus 

 with a distinct nucleolus. At the anterior end was usually a very 

 slight notch. In most cases there was no flagellum ; but in a 

 considerable number a flagellum was present and exerted a con- 

 siderable influence on the movements of the animal. 



The movements of the animals within the cells were very 

 remai'kable. They seemed rarely to be at rest, almost incessantly 

 creeping actively round and round the interior of the cell. Some- 

 tii'^ies they could be distinctly seen to brush aside filaments in the 

 cell-protoplasm, sometimes to thrust on one side the nucleus, 

 restrained always apparently within the interior of the cell by a 

 firm membrane which resisted perforation. Usually there was 

 only one in a cell ; frequently there were two, occasionally even 

 three. In several cases they were observed to be undergoing 

 multiplication by fission — the division beginning, as represented 

 in figure 1, at the clearer anterior end. 



