176 NATURAL SCIENCE. march. 



In the course of from five to seven minutes there would supervene an 

 amoeboid condition, not striking, but still visible, as shown in H, Fig. 

 6, where the body-substance would oscillate from the hollow condition 

 shown to the lateral expansions indicated by the dotted lines at 5, t, a 

 vacuole — curiously like an " eye-spot " — would appear, exhibiting very 

 marked opening and shutting, as at v ; and the nucleus, u, was driven 

 to the middle of the body, greatly enlarged, and, losing its nucleus- 

 like aspect, was torn apart in irregular halves ; meanwhile, a very 

 strong sigmoid division-line, shown in J, Fig. 7, at w, x, became 

 extremely marked, and the divisions of the nucleus were pushed one 

 on each side of this line, as at tc^ and x. At this time a point of pro- 

 toplasmic material was pushed out, as at y, dividing into two fine 

 threads. 



A gliding motion now ensued, by which w glided off" from x ; 

 this is seen at Fig. 8, k, a, (3, showing two normal forms nearly freed 

 from each other in this way ; but in our earliest work it was quite 

 manifest that the nuclei of these two forms had quite strikingly 

 changed, having undergone some radical alteration, and trailing 

 flagella were formed at z, partly by growth and partly by division. 



Soon after total freedom from each other, these modified forms 

 swam freely for some minutes, and then directed their motion to 

 some part of the field where the ordinary forms (with the usual 

 nuclei) were in greatest abundance, and almost immediately what 

 was seen to be an act of fusion commenced. The initial stage is 

 shown in Fig. 9, L, where the unlikeness of the nuclei is seen at 



r, 5. 



The fusion takes place rapidly up to a certain point, for in 

 eight minutes a large part of the body-substance of each has fused 

 with the other, as seen in 10, M, where the nuclei are fully united, 

 and a radial or star-like diffusion takes place-, as seen in ■>] ; and this 

 continues, growing fainter and less perceptible for an hour, or some- 

 times an hour-and-a-half, until it wholly disappears, and all trace of 

 nucleus is gone, the mass of the plasm of the combined cells being 

 faintly granular, or perhaps reticulated ; but the trailing flagella (6) 

 fuse together and unite with the body, which now rapidly changes, so 

 that in the course of fifteen minutes it assumes the shape and con- 

 dition shown in Fig. 11, N. At the end of four hours a kind of 

 pulsating movement shows itself in this triangular sac, and at length 

 it burst one or two, and sometimes (as in Fig. 12,0) the three corners 

 of the triangular sac, and an enormous number of semi-opaque and 

 extremely minute particles, escaped (Fig. 12), and by watching these 

 they were seen to pass by growth into forms corresponding to the 

 common form from which they arose. 



These observations were made in the original and renewed study 

 of the behaviour of this organism as a whole ; but during the past 

 three years the greatly superior microscopic apparatus, both illumi- 

 nating and image-forming, placed at our disposal, has led to an 



