OF THE PROTOZOA. RHIZOPODA. 215 



individuals in different stages, Schnltze never saw accompanied by a con- 

 nexion between two animals ; and he was not able to discover what subsequent 

 changes awaited the spherical body produced. 



The phenomenon just considered appears to us to be analogous to the 

 encysting process recounted by Schneider in the case of Amceba, and by 

 Stein in so many Cihated Protozoa. 



Two other probable modes of reproduction are briefly noticed by Schneider, 

 but requii'e to have theii^ existence confirmed by fiu'ther observations. " I 

 have observed," he says, " another mode of propagation in our Difflugice ; 

 and although my obseiwations have certainly not been frequent, they have 

 been sufficiently satisfactory. After I had kept a great number of these 

 creatui'es for some weeks in a clayey sediment, the substance of the body 

 in all the individuals contracted into a ball. All foreign substances had 

 previously disappeared. The ball, which had a fatty outline, then divided 

 into two and four parts ; but the nucleus could not be traced dming this pro- 

 cess (XXI. 19 d, e). This investing membrane fell to pieces, and the little 

 spheres Avhich may perhaps be regarded as four quiescent spores, were no 

 more to be seen. 



" Whether another circumstance observed by me has any connexion ^\dth 

 the reproduction of Difflugia must be ascertained hereafter. In all the 

 indi\iduals of Difflugia contained in one vessel, the substance of the body 

 became converted into granules closely packed together, the form and the 

 investing membrane being retained (XXI. 19 c). I often saw these granules 

 in quick molecular movement in the interior of a sac, which appeared to be 

 formed from the outermost layer of the body, but I watched in vain for any 

 issue to this ; after moving about for about half an houi% the granules always 

 became quiescent again." 



A note by Perty must not be omitted, although no considerable importance 

 can be assigned to a solitary and ambiguous observation. That naturalist 

 tells us he " once saw two round motionless animals within an Arcella vul- 

 garis, each having a much greater diameter than the mouth of the sheU con- 

 taining them. Were these," he asks, " young beings to be set free on the death 

 of the parent and the breaking up of the shell ? " A somewhat similar fact 

 is recounted by Schultze of Gromia Dujardinii, in one large specimen of 

 which he found several oval bodies enclosed possessing a firm envelope and 

 granular contents, and representing in every respect young Gromia, except 

 in ha^-ing no evident opening in their shell, which, however, may possibly be 

 formed when set free from the parent (XXI. 18). 



That the piu-pose of the nuclear bodies in Gromia oviformis (see p. 211) is 

 not connected with the function, Schultze feels compelled to assume, princi- 

 pally from the absence of such nuclei in Ehizopoda generally, and from his 

 having failed to observe their undergoing those changes known to occur in 

 true nuclei when the generation of new individuals is in progress. 



Yoimg Arcellina, when first recognizable as such, have the general form of 

 older individuals ; but theii' shells and tissues are much more transparent, and 

 at first colomless and without granules. But it is very probable that the 

 young of many Arcellina, when fii^st thrown off from the parent, are naked — 

 destitute of shell, — a \iew supported by an observation of Cohn, who records 

 having seen, amid the sUmy matter about living Difflugice, a large number of 

 pecuHar animalcules consisting of a contractile greyish or bro^vn finely- 

 granular substance, about J-th of a line in diameter and upwards, of a roimd, 

 ovoid, or angular outline, and having a muco-gelatinous envelope, through, but 

 chiefly at one end of which several fibres were extended. At a stiU earlier 

 period these young beings may therefore be presumed to have been mere 



