of the Poly gastric Infusoria. *&ti 



ner at two spots, as shown in fig. 10 b. The granules thus 

 arranged and closely pressed together blend into a glandular 

 but clear organ, in which the granular structure cannot be any 

 longer detected ; frequently it is also divided into two parts, figs. 

 11 and 12. Lastly, in the situation of the transparent glandular 

 organ a row of cilia appears, evidently the mouth (fig. 13 a) ; but 

 whether the latter is formed immediately from the former I have 

 not been able to ascertain with certainty, but it is extremely 

 probable, since on the one hand the row of cilia occurs in the 

 situation of the bright gland, whilst, on the other hand, in all 

 the germs which exhibit this the former organ is absent. Si- 

 multaneously with the development of the mouth there appear 

 one or two clear vesicles (figs. 13, 14 b). On the 18th of May 

 I observed in the interior of St. cceruleus a germ as in fig. 13 ; I 

 saw the cilia very distinctly in motion ; the vesicles were however 

 still absent, and they did not escape on this occasion. On the 

 21st I saw the perfect form, fig. 13, which issued out, whilst the 

 parent animal swam away. I now attentively observed the young 

 one to follow up its further changes, perhaps the bursting of the 

 carapace ; but I was obliged to leave off watching it in half an 

 hour, as I could not vouch for the accuracy of further observation 

 on account of the strain upon my eyes. On the 4th of June I 

 saw a germ escape, as in fig. 14 ; it differed from that observed 

 on the 21st of May, for, being at first round, it at once exhibited 

 an incurvation at its lower extremity, an appearance frequently 

 observed in young Stentors, sometimes in old ones, when they 

 contract from the elongated form to one more or less rounded. 

 I have subsequently once seen the escape of a similar germ, and 

 it appears to me that the true point of maturity is that at which 

 vesicles begin to be visible. In Stentor polymorphus, fig. 15, I 

 have observed two such globules, but I have not succeeded in 

 seeing any perfectly formed escape. In autumn I have often 

 sought for the recurrence of this phenomenon, but have never 

 been able to observe it so perfectly as in the spring, although 

 similar globules are not rare in the later parts of the year. 



How can we explain this phenomenon ? It can hardly arise 

 from Vorticella which have been swallowed, as has been proposed 

 to me in conversation, since I observed such various conditions 

 of development, which were moreover never observed except in 

 one part of the body, never more anteriorly, which is hardly 

 possible if they were substances which had been swallowed. I 

 rather think it formed the earliest commencement of the forma- 

 tion of buds, which usually appears at this part of the body. 

 But it is also possible that it is a peculiar kind of propagation, 

 which Steenstrup* and others have observed in many intestinal 

 * On the Alternations of Generation. 



