Natural History of the Vorticellaj. 209 



on all sides from the circular point of attachment of the 

 peduncle. In this position of the animal, especially when, 

 without being compressed, it rests with its opened anterior 

 ciliated disk upon the glass plate and stretches its base upwards, 

 we may also obtain, in certain positions, the clear view of a 

 transverse section of the body (see PL XIV. fig. 8). At the 

 outside there appears a clear border {cuticula), which is di- 

 stinctly limited within ; then follows a circlet of dimly shining 

 corpuscles (the luniina of the muscular fibres) j and further in, 

 again, a clear zone {cortical layer) ^wh.\c\\,diii parenchyma jentirely 

 fills the conical hinder part of the body, but becomes thinner 

 anteriorly, and encloses the true body-cavity. Within the last 

 clear layer of parenchyma we then see, in Vorticellte witli 

 contractile pedmicles, some dark corpuscles arranged in a circlet; 

 these may be regarded as the fibres of the peduncular muscles 

 radiating in the body. 



If the body of a Yorticellan be gradually compressed until it 

 is completely flattened, granules, all of the same size and in 

 apparently regular arrangement, make their appearance be- 

 neath the cuticula. In general we seem to recognize a distinct 

 longitudinal direction, con-esponding to the course of the mus- 

 cular fibres (PI. XIV. figs. 1, 5) ; but it is very possible that 

 this is an illusion, as the longitudinal fibres of the muscles ap- 

 pear at the same time and in the same place. Sometimes, also, 

 especially during long-continued compression, it is difficult to 

 ascertain that they have any definite direction. Whether they 

 can be brought into connexion with the muscles, or whether 

 they belong to the lower surface of the cuticula, or, lastly, to the 

 cortical layer of the body, I cannot decide at present. These 

 are, no doubt, the same structures already mentioned by Ley- 

 dig *, and which appeared to him to have " quite the habit of 

 nuclei." I admit that on viewing these peculiar corpuscles, 

 their regular arrangement and their always definite size and 

 limitation, I was frequently inclined to adopt the opinion of 

 this distinguished naturalist, and to regard them as the nuclei 

 of the cortical layer or of the muscles. But for this it is ne- 

 cessary, in the first place, to accept the supposition that nuclei 

 and cells of such minuteness as the corpuscles in question 

 really exist, which, although we cannot reject it out of hand, 

 is yet by no means founded upon observation. Perhaps, liow- 

 ever, further investigation, especially upon the development of 

 the Vorticell*, may furnish an answer to this question, which 

 is by no means unimportant towards our conception of the 

 structure and, through this, of the position of tliese ani- 

 malcules. 

 * Lehrbuch der Ilistologie des Mensch. uiid der Thieve, pp. IG & 125. 



Ann. & Mag. Nat. Hist. Ser. 4. Vol.\yi. 15 



