as Infusoria flagellata. 195 



(fig. 10, cv) of these vesicles are found together ; but it has 

 always been evident at such a time that the body was prepa- 

 ring for fissigemmation (figs. 9, 10), and that the increase in 

 number of these organs arose from the fact that one of them 

 had already undergone self-division. In another genus {Sal- 

 pingoeca^ 8. marina, nov. sp., figs. 28,29,30) no less than four 

 contractile vesicles {cv) have been observed to arise from two, 

 under the same circumstances. 



The systole of each vesicle of Codosiga occm's regularly 

 once in half a minute, and usually that of one alternating 

 with that of the other. Both the systole and the diastole pro- 

 ceed very deliberately, each, however," not occupying more than 

 a few seconds. During the interval between the end of the 

 diastole and the beginning of the systole the vesicles have a 

 rather irregular, indefinite, spheroidal outline 5 but just at the 

 moment of systole they assume a sharply defined and perfectly 

 globular shape, and raise the surface of the body into a quite 

 perceptible bulge. During this momentary expansion a vesicle 

 equals at least half the greatest diameter of the body. 



The reproductive organ, if we are not mistaken in our inter- 

 pretation, is seated at the posterior end of the body, behind the 

 contractile vesicles. It is a globular, highly transparent body 

 (figs. 23, 24, w), and sometimes almost fills the space on each 

 side of it. That it is solid, and not a mere vacuole, appears 

 conclusive from its resilient action after being indented by the 

 expansion of the contractile vesicles. It should be mentioned 

 that this body was not observed in the fresh specimens which 

 M'^ere collected in December, but appeared to be constant in 

 some stale examples which had been kept on hand for two or 

 three months. 



^\\e, peduncle (fig. 8,^:»c?), or main support of the colony, and 

 the pedicels {pd"^) or immediate bearers of the individuals, 

 share in the general gamboge-yellow colour of the latter, and 

 also in their vitality. The latter statement has been verified 

 fully in regard to the pedicels, by seeing them split down to 

 their bases after the body proper has undergone self-division j 

 and in regard to the peduncle, although only one observation 

 was made, and the splitting was followed in its slow course 

 downward for only a short distance, it was evident, from its 

 much more than usual thickness and the presence of a distinct 

 median furrow which extended to its very base, that it even- 

 tually would divide into two stems. The length of the 

 peduncle varies from a mere disk, when it begins to develope 

 from the base of some newly settled Monad, to five or six 

 times the length of an individual. It always carries a single 

 body until it is at least three or four times its length (figs. 9, 



