as Infusoria flagellata. 197 



the slightest possible tremulous vibratory motion. Within a 

 very few minutes after this, the flagellum began to shorten as 

 if retracting, reminding one of the running down of a cotton- 

 thread in the flame of a candle, and in one minute's time it be- 

 came reduced (fig. 12, Ji) to a length which was somewhat less 

 than half the height of the collar {b), and then it rapidly dis- 

 apjjeared and left no trace of its former position. During this 

 process the body shortened and became broader (fig. 12) in the 

 same direction that the plane of the arc of the flagellum for- 

 merly trended in, and consequently the contractile vesicles {cv) 

 were more widely separated ; and the front {fr) also having 

 become pro23ortionately extended laterally, the base of the col- 

 lar (b) was also increased in diameter until it almost equalled 

 that of the distal end, so that, as a whole, it was almost cylin- 

 drical. 



In less than fifteen minutes after the preparatory stage was 

 observed, the collar had become cylindrical (fig. 13, b) by a 

 combined action of the base and distal end, which consisted in 

 a narrowing of the latter and a broadening of the former. 



It was not until 1.15 p.m. that a decided mark of incipient 

 self-division became evident in the guise of a narrow, slight 

 furrow (fig. 14:, e), which extended, medianly, from the front 

 to over halfway toward the posterior end of the body. By this 

 time the body had broadened until it was wider than long, and 

 the collar (b), having followed this expansion at its basal por- 

 tion whilst its upper extreme had contracted a little, had as- 

 sumed the form of a high truncate cone. 



In two or three minutes after this, the body had become 

 distinctly indented (fig. 15, e^) at the anterior termination of 

 the furrow (fig. 15, e), and the latter had grown longer and 

 more distinct, whilst the collar [b] had approximated more 

 closely in shape to a perfect cone. 



In another minute or two the anterior indentation (fig.l6,e^) 

 had become so deep and broad that the body presented a 

 cordate outline when seen from its broader aspect, whilst the 

 fiuTow (e) appeared to extend to its base, and the distal end of 

 the collar (b) had so nearly closed up as to give that body an 

 almost completely conical form, with a slightly collapsed 

 periphery. 



From this moment the process of reduction ceased; and soon 

 after, the cone-shaped collar began to expand (fig. 17, b). Con- 

 sentaneously with this, the anterior indentation (e^) had be- 

 come sharper and deeper, and (with the lateral median furrow 

 (e) of each of the opposing broad flanks of the infusorian act- 

 ing in combination with it) had split the body about halfway 

 to its base. The most remarkable phenomenon observable at 



