206 Transactions of the Society. 



crowded gatherings of this organism which are "anchored" and 

 springing upon, in order to break ap, specks of decomposing 

 matter.* It there firmly attaches itself to one of these active 

 springing forms, which at once nnanchors itself; and both together 

 swim freely and vigorously about as seen in fig. 10. In the 

 course of from thirty-five to f'^^ty-five minutes they become inert ; 

 the lateral flagella of the lower ^oiiLa fall upon and become fused with 

 the mass of the body-sarcode ; the front fiagella become entangled 

 and melt together, and during the whole time the two bodies are 

 dissolving into each other. But there is a visible difierence in the 

 nuclei. The nucleus of the metamorphosed one remains large and 

 retains its whiteness, as at &, fig. 10. That of the lower and ordinary 

 one is small and highly refractive with a slightly brown colour, as 

 seen at a, ibid. 



When the uniting organisms reach the state shown in fig. 11, 

 they are absolutely still, and the two nuclei coming into contact, 

 fuse together : but the lower and smaller one becomes lost in, and 

 takes the optical character of the larger, as it melts into it ; but to 

 the last that part of it which is not absorbed, as seen at a, fig. 1 1, 

 retains its own character. But very soon the two nuclei become 

 one — a pale white oval body — and the body-sarcode unites wholly 

 together in a spindle or long oval form, as seen in fig. 12. The 

 nucleus becomes fainter and fainter to every reagent and every form 

 of illumination ; but it can be seen, as in fig. 12, to be diffusing 

 itself in a star-like or radial manner through the sarcode until it 

 is no longer traceable, and we have a tight, glossy, whitish, 

 spindle-shaped body, seen in fig. 13, from which, at the end of from 

 three to four hours, the germs are emitted, from which a fresh 

 host of this organism arises ; shown in fig. 8, plate VII. 



Now by my latest investigations I was able to demonstrate that 

 in this case, as in the preceding, all the changes that arose in the 

 last product of fission began in the nucleus. The first vital 

 divergence from the normal form previous to fission was not the 

 amoeboid state shown in plate IX. fig. 8, but a change from the 

 highly refractive and plexus-like condition of the interior of the 

 nucleus, into the white, structureless, and much enlarged nuclear 

 body seen at &, ibid. : and then follow all the changes I have described. 



That we have in this union of the nuclei of two separate forms 

 of the same organism, followed by a union of both body-sarcodes, 

 a distinct act of fertilization, it would be almost idle to doubt. It 

 is a curious fact that whilst in each of the earlier activities of the 

 nucleus there was a discoverable structural condition, in this most 

 important action in the life of the nucleus there is a loss of 

 all differentiation. The whiteness is very striking, and the 



* Proc. Roy. Soc. ibid. 



