OF THE PROTOZOA. CILIATA. 345 



top of the bulb ; and at ten it had divided longitudinally into two buds, each 

 supported by a short stalk. The ciliary motion continued in the centre of 

 each of these two buds, which by degrees expanded longitudinally, and at 

 twelve had become foiu' buds. By four in the afternoon, these four buds had 

 divided in like manner and increased to nine, with an elongated foot-stalk, and 

 interior contractile muscle. 



" Dming the development of another specimen, the stalk ai^peared to have 

 transverse ribs or joints, and, whilst a drawing was making, gradually bent 

 do^vn wards, and all the buds severally detached themselves from it, and w^ent 

 off as free animals, leading only the bent stalk. In this interesting process 

 we see something analogous to what Steenstrup describes as ' a mode of 

 development by means of niu'ses or intermediate generations.' 



*" This mode is described as that in which an animal produces a progeny 

 pei-mancntly dissimilar to itself, but which progeny produces a new generation 

 in itself or its offspiing, returning to the form of the parent animal. It 

 will be seen that this development differs from that of metamorphosis in 

 - the cii'cumstance of the intermediate animal (the nurse) being itself a perma- 

 nent and producing form. 



'• To show this to be the case \^dth Zoothamnium, it would be necessary to 

 prove that the medlar- shaped animals were a permanent form, producing a 

 race which, in themselves or in what they produced, returned to the form of 

 the parent animal. 



*•' We have not been able to carry the development of these buds or ova 

 further than PI. 12. f. 67, 68, 69, and wood cut " (see Part II.). '^ And it is 

 remarkable that in aU these the buds have produced, not the little beU-shaped 

 animalcules like the parent animal, but other buds like themselves. May it 

 not be the case, that these medlar-shaped bodies are propagated at the close 

 of the year, and that, when the plant to which the Zoothamnia bearing these 

 bodies are attached dies away, they remain in the mud, protected from the cold 

 of the T\anter, and in the spring burst forth, and settle upon the new-gro^dno- 

 plants, and produce animals of the parent-fonn. They would thus form an 

 intermediate nursing race answering to Steenstrup's description." 



Prof. Cienkowsky has witnessed (Zeitschr. 1855, vi. p. 301) cyst-construc- 

 tion in NassuJa vlridis (Duj.) (XXYIII. 65 — 71), Stylonychia jpustulata 

 (XXYIII. 74 — 76), >S^. Icmceolata, in various VorticeUce, in Bursaria trunca- 

 tella, B. Jateritia, Poclo^hrya jixa, Loxodes CucuUulus fDuj.), Leucophrys 

 Spathula, AmphUejotus margaritifer, Ilolojohrya brunnea, and less completely in 

 Amphileptus Anas, Stylonychia Mytilus, Paramecium chrysalis, Spirosiomum 

 ambiguum, Stentor po(ymorj)hus, St. Millleri, Paramecium AureJia, and Loxodes 

 Bursaria. 



In Loxodes Cvcidhdus (Duj.) and Stylonychia pmstidata he saw the dis- 

 charge of the whole of the contents of the cyst in the form of encvsted Infu- 

 soria. The embiyo born from the cysts of Stylonychia pustulata resembles 

 closely the Triclioda Lynceus, and can multiply itself by self-fission just in 

 the same manner as mature and independent beings. 



In cyst- development, he observes, the whole of the contents are, as Jules 

 Haime stated, not metamorphosed into the resultant embryo, but one or more 

 portions escape in the form of globules, apparently ciliated, and move off with 

 a rotating motion. 



PEPEonrcTiox of the Ciliated Protozoa: — Fission, modes of; Gemmation- 

 INTERNAL Ova producing Ghrms or Embryos ; Impregnation ; Production 

 of new Beings a^ith and without Metamorphosis ; Transformation into 

 Acinet^, and Development of Embryos. — Until lately, naturahsts in general 

 did not acknowledge other methods of reproduction than by fission, or, as 



