70 Transactions of the 



depression — as drawn in Fig. 5. We observed this repeatedly with 

 every variety of appliance, and the utmost power we could use, but 

 we could discover no premonition of its appearance. There was a 

 sudden transition from the condition drawn in Fig. 4 to that in 

 Fig. 5. These lines now rapidly increased in number and became 

 curved as seen in Fig. 6 ; and from this time deep indentures or 

 incisions ensued, and an intense activity was set up all over the 

 sarcode — a sort of interior whirling motion, which we can think of 

 nothing better to assist us in describing than the rush of water 

 round the interior of a hollow glass sphere on its way to the jet of 

 a fountain. This would last for from ten to seventy minutes, when 

 the sarcode would cease its activity, and very rapidly break up into 

 the condition drawn at Fig. 7. There was no trace of an investing 

 membrane ; the constituent parts were related to each other simply 

 as the two separating parts of sarcode in an ordinary fission, and 

 they commenced a quick writhing motion upon each other like a 

 knot of eels; and in this state they remained for a somewhat 

 indefinite period, but usually from seven to thirty minutes, when 

 they either one by one left the mass — free- swimming and flagellated 

 monads — or, more usually, broke up altogether as seen in Fig. 8, 

 and swam freely over the field as in Fig. 9. The only dift'erence 

 between them and the form which had yielded them was that they 

 were smaller ; but this difference in size rapidly disappeared. 



These were the prevailing phenomena — at least those that were 

 most readily seen ; and this process might be the only one observed 

 for days or even weeks. Indeed, we should have accepted this as a 

 complete cycle, but for our former experiences. 



At length by careful and constant scrutiny we perceived scattered 

 among the rest forms of the same monad somewhat larger and 

 plumper than the rest, and with a singular granular aspect towards 

 the flagellate end. One of these is drawn at Fig. 10. These 

 became more numerous, and we observed that they fastened them- 

 selves upon the ordinary forms, much in the same manner as was 

 described in our last communication. Fig. 11 illustrates this some 

 fifteen minutes after attachment ; both forms freely moving their 

 flagellum, and the pair swimming briskly over the field. There 

 was a palpable absorption of the lesser by the greater, but the 

 length of time this occupied was extremely various. When it was 

 complete, there was no immediate change in the monad ; it swam 

 freely as before, but at length became more sluggish, and in the 

 course of from two to six hours settled as a slightly flattened 

 spherical body, the flagellum of which was seen slowly moving for 

 a short time, but afterwards disappeared. 



The length of time which these bodies remained in this con- 

 dition was extremely uncertain ; we have known them so remain, 

 and, as the sequel proved, retain vitality for over thirty-six hours. 



