Prof. C. Gc'genbaiu' on Trachclius ovum. 203 



it appeared to be a longitudinal cleft, which closed again in a 

 moment, and left no trace after the walls of the extremity of the 

 canal had come in contact. The frequent union of the end of 

 the trabecula in question with the opjjosite wall of the body, 

 its delicacy, which often causes it to ap])ear like a fine filament, 

 the constancy of the size of the external orifice, and the circum- 

 stance that balls of food were never to be seen in its vicinity, or 

 indeed in the anterior portion of the body generally, — lead me 

 to conclude that this anterior a])erture has nothing to do with 

 the reception of aliment. 



It has already been nieutioncul, in the description of the buccal 

 orifice, the " intestine/' and the trabecular system, that there is 

 a "general cavity" [Leibeshohle] , and 1 regard this as not unim- 

 portant in judging of the nature of this creature. The general 

 cavity never contains food ; and even when particles of food 

 project into it from the so-called " intestine^' and the trabeculse, 

 they are still always enveloped by a distinctly perceptible layer 

 of the finely molecular substance of the body. The general 

 cavity is filled with a clear fluid, which never contains any 

 distinctly formed parts. I regard this fiuid as water, and must 

 suppose that it is admitted through the above-mentioned canal. 

 I have not seen this take place, and experimental feeding with 

 colours gave no result, probably because the delicate cilia stand- 

 ing round the small orifice prevented the entrance of molecules. 

 On the other hand, 1 am convinced that water is nevertheless 

 admitted. 



Thus, when I had been for a long time observing an animal- 

 cule imprisoned in a narrow space, it happened, nearly every 

 time that I could wait long enough for it, that it suddenly con- 

 tracted strongly ; the trabeculte shortened themselves, and the 

 form, which w^as originally full and tense, shrank into a de- 

 formed, irregular, and folded mass. I thought that I should 

 now see the itio in pnrtibus take place, but, by continued ob- 

 servation, I found not only that no particle separated from the 

 shrivelled body, which was evidently reduced in size much more 

 than half, but that the animal even continued to swim about 

 briskly. How little injury had been suffered by such a specimen 

 was evident when I put it into a more spacious capsule, for it 

 then very soon acquired the same form and size as before, and 

 on comparison with figures previously prepared, exhibited no 

 change, except that some trabeculse had become amalgamated 

 together, whilst others had made their appearance. I have re- 

 peated this observation several times, and always with the same 

 results. How can the considerable alteration of volume be ex- 

 plained, except by the consecutive loss and reception of water ? 



