DUBLIN NATTJEAL HISTORY SOCIETY. 33 



nal spaces, of course, excepteJ. Oa the whole, then, it does not appear 

 to me that these swarming granules had anything specially to do with 

 the production of the very different motile bodies now to be described. 

 I have before stated that the endochrome near the base of each seg- 

 ment, and filling the lateral tubes, becomes very finely granular ; it next 

 becomes segmented into a definite number of rounded portions, or "go- 

 nidia." I was never able to count them exactly, but I suppose they 

 were not less than twenty, nor over fifty ; nor did the fact of there being 

 either two or three lateral tubes developed seem to indicate any very 

 great addition to the number of these bodies. That portion of the endo- 

 chrome not thus transformed into gonidia lying beyond them, and 

 extending to the ends of the segments, by this time loses its normal cha- 

 racter, and seems to become drawn into detached bands or strings, with 

 a few free granules, and the terminal cavity, with the active particles, 

 becomes lost. The gonidia lately formed at the middle of the frond 

 have now emerged through the opened apex of the lateral tube, and re- 

 main clustered together in a mass very much like a bunch of grapes, the 

 clusters becoming, by degrees, larger and larger, until all the gonidia 

 make their exit through the tube, and each adds its quota to the group 

 (Fig. 3). The same is the case when there are two or three tubes, the 

 only difference being that a fewer number, but generally about equal, 

 make their way through each (Fig. 4). Meantime, the unused endo- 

 chrome, which had become drawn into detached strings, now loses its 

 bright green colour, changing somewhat to an olive, finally turning 

 brown, and quite dying, and even, to a great extent, disappears (Figs. 3, 

 4). Each of the gonidia forming the external cluster appears by this 

 time to have formed for itself a special cell- wall of slightly compressed 

 or elliptic form, within which the green contents may often be seen 

 somewhat retracted. JS^ow, a movement within its circumscribed prison 

 may be seen on the part of the contents of a few of the gonidia, which 

 takes the appearance of a twisting motion, backwards and forwards, as 

 it were on its axis, similar to what may be sometimes seen in the or- 

 ganisms called Trachelomonas by Ehrenberg. I have not noticed them 

 to turn completely round. These gonidia are, however, greatly smaller, 

 nor could I perceive any red spot. If such a comparison might not ap- 

 pear wholly out of place, I would be induced to say that the movement 

 of the green contents within the confining membrane reminded me 

 somewhat of the movement of the eye in certain Entomostraca. This 

 movement is not apparent in all the whole group of gonidia simulta- 

 neously, but only in a few at a time. Eventually, one by one, the green 

 contents leave the confining membrane in which they have hitherto 

 been detained ; but my observation being here incomplete, and my avo- 

 "cations calling me away, I am unable to say in what manner they made 

 their exit. There certainly appeared no neck-like opening or perceptible 

 aperture, but they probably emerged by rupturing the boundary wall. 

 Having, however, made their escape, they swim away as ovate or pyri- 

 form ciliated bodies, pale at the narrower or pointed end, and green 

 otherwise throughout — in point of fact, veritable motile gonidia, or 



