446 M. Eckhard on the Organization 



what similar occurrence is seen in Stentor caruieus, to which I 

 shall recur presently. Siebold appears to have overlooked this ; 

 for at p. 23, as the means of propagation of the Polygastrica, he 

 only enumerates division and the formation of buds. 



2) By Zygosis. — This has hitherto been observed in the animal 

 kingdom only in the Closterina. In autumn we find young Closte- 

 ria of such a form, that two globules, each of which is elongated 

 on both sides into a point, have become adherent. Unfortunately 

 their further stages of development have not yet been seen. We 

 do not know whether perfect Closteria are formed by an intimate 

 growing together of the globules with their elongations or by a 

 progressive separation, although the former is probable. Should 

 we be so fortunate as to clear up this point, and should the zygose 

 prove to be a mode of propagation of the Polygastrica, it would 

 not be so rare hereafter ; for it has also been observed in species 

 of Spirogyra and a mould-formation. 



3) By division. — This occurs either transversely or longitudi- 

 nally, or in one and the same species in both directions. It is 

 evidently, in many families, one of the most productive methods 

 of propagation, as in the Bacillai'ia, Kolpodea, Stylonychice, &c. 

 In the former the siliceous carapace divides regularly, and this 

 might perhaps form another ground for enumerating them among 

 animals. 



4) By formation of buds. 



5) Formation of ova has certainly not been directly observed, 

 but the different sizes in which many Polygastrica, especially 

 Vorticella, occur, perhaps allow us to conclude in favour of its 

 existence. The difference in the size of Vorticella microstoma is 

 most remarkable. In no instance could the individuals of this 

 species, which are all so very small, be produced by division ; 

 nor by the formation of buds, for such has not yet been observed 

 in them. I shall here mention an observation which I made in 

 the early part of 1845 upon Stentor cceruleus to connect the 

 further reflections on this point. 



Plate X. fig. 7 exhibits this Infusorium. Within it I observed 

 three or four globules in different states of development, which are 

 represented in a row in figs. 8 — 14. In the first stage the con- 

 tents of the globules, consisting of minute granules, exist most 

 imperfectly developed; but few granules at present occur, and 

 the globule, when it lies in the body, is not very distinct on ac- 

 count of the granular parenchyma of the latter. In the second 

 stage of development, fig. 9, the granules appear more numerous, 

 the contents are therefore more concentrated, and the globules 

 can then be very distinctly observed in the body. Fig. 10 a 

 shows the third stage ; granules commence arranging themselves 

 in a row m. They sometimes appear grouped in the same man- 



