198 Prof. H. James-Clark on the Spongiae ciliatse 



this time was what occurred at the rounded ends of the two 

 half-separated bodies of the new pair of individuals. This was 

 no more nor less than the incipient development of the flagel- 

 lum, which proceeded in this wise : — At each of the rounded 

 ends just mentioned a slight commotion appeared, resembling 

 the molecular vibrations of a granule ; and then there arose 

 quite rapidly a sharp and distinct filamentous outgrowth (/), 

 which kept itself in a constant state of narrow vibrations, or a 

 sort of shivering. 



By 1.23 P.M. the newly born flagella (fig. 18, j^) had risen 

 to half the height of the collar (^), and still remained in a 

 shivering condition, whilst the body had divided almost to its 

 base, and the collar had broadened to a widely terminating 

 truncate cone. 



In about a minute more, the dividing process had risen into 

 the collar and split it (fig. 19, e^) upwards for one-quarter of 

 its height ; and the still tremulous flagella {fl) were slightly 

 longer than in the last phase. 



By 1.26 P.M. the body was divided (fig. 20) to its posterior ter- 

 mination, and the fissuration (e^) of the collar [h) had reached half- 

 way to the distal edge, and was further sketched out as it were 

 by two opposing shallow longitudinal furrows, which extended 

 to the margin. At this period the collar was broader at the 

 still undivided portion than below ; so that on the whole it had 

 a very wide campanuliform shape, or rather (since the divided 

 portion was rolled inwards at the opposing edges) was like 

 two slightly flaring, broad funnels, merged into each other at 

 their broader ends. The flagella {jl) also had developed con- 

 siderably, and extended a short distance beyond the collar ; 

 and the front end of the body, from the middle of which the 

 flagellum arises, had assumed the low, trmicate, conical shape 

 of the adult form. 



From this time onward the division did not appear to go 

 forward so rapidly ; and the new bodies seemed to be more 

 particularly occupied in shaping themselves into the charac- 

 teristic form of the adult. The collar, however, was not long 

 in dividing itself up to its margin (fig. 21), but still the two 

 cylindi'ical halves (Z), h) did not separate at their extremes as 

 soon as the fission reached that point. 



At 1.35 P.M. the self-division was completed (fig. 22), as far as 

 the body proper was concerned, and had extended a short way 

 down the pedicel ['pd'^). The margins of the two collars {b) 

 seemed merely to lie in contact; and each collar had a slightly 

 funnel-shaped outline, and was considerably more elevated in 

 proportion to its diameter than in the adult form. The flagel- 

 lum [ji) was nearly as long as that of the full-grown body. 



