Royal Microscopical Society. 9 



enabled to demonstrate that the filament a, b, snapped in the middle 

 and flew back in a coiled condition, as seen in a, a, Figs. 6 and 7, 

 and in a more advanced state of occlusion at a, a, Figs. 8 and 9 ; 

 and very shortly this delicate coil, which was repeatedly seen, al- 

 though always with difficulty, became lost in the sarcode. 



We now carefully watched the initial stages in fission, and were 

 enabled to discover with the first evidence of constriction the shoot- 

 ing out of a short coil at the non-flagellate end as drawn at c, 

 Fig. 3 ; this was increased by another coil and a rapid whip-hke 

 motion until the entire flagellum c, Fig. 4, was thrown out. Thus 

 there appeared to be a utihzation of a reserved flagellum, produced 

 originally by fission. The mode of origin of the hook has eluded 

 us; but it appears to arise from an extrusion of sarcode. Each 

 half of the divided monad is thus equally difi'erentiated before final 

 separation. 



As in all the other instances we have observed, multiplication by 

 this method continued with no apparent interruption for several 

 days. But in our prolonged observations on the mode of fission we 

 had repeatedly seen two of these monads uniting; that is, one 

 would apparently fix on the body of another. On closer examina- 

 tion we saw that the contact was not necessarily permanent ; but 

 where it was the following facts were repeatedly seen. One monad 

 with a sort of eye-spot, h, Fig. 10, PI. XL VII., and a knot at the 

 end of the flagellum a, ibid., would fix on the sarcode of another 

 without it, and the substance of the lesser or under one would be 

 absorbed by the upper ; the latter increasing palpably in bulk, as 

 seen in Figs. 11 and 12, whilst the eye-spot b soon began to open 

 and shut, and gradually to increase in size. Eventually — in about two 

 hours — the merest trace of the lower one was left, Fig. 12 : and the 

 flagellum a moved sluggishly, and in another hour it had anchored 

 as in Fig. 13, and the eye-spot b had reached its largest size and 

 most constant motion. In the course of from forty minutes to four 

 hours this ceased ; all trace of the eye-spot was lost, and a yellowish 

 gelatinous-looking flabby mass resulted, which is shown at Fig. 14, 

 and was severed from the flagellum a. Distension rapidly ensued ; 

 so that a spherical form was taken by the mass ; and after repeated 

 watchings on forms in the same condition it was made out with a 

 power of 3500 diameters, that openings at a, b, Fig. 15, appeared, 

 and a faint line connected them. In less than five minutes after 

 they appeared also at c, d, Fig. 16^, with a faint line at right 

 angles to the first ; and in ten minutes after it had taken the form 

 shown in Fig. 17*. From this time an internal division in all 

 directions took place, represented in diagram rather than in actual 

 portraiture, at Fig. 18. The activity that now displayed itself 

 within this tiny ball can scarcely be conceived, for the whole interior 

 sarcode in about three hours had broken up into innumerable 



