OF THE PROTOZOA. CILIATA. 353 



lualeule and its sheath. Tlie rule seems to be that two or four gemmae are 

 produced within the sheath at the same time (XXX. 29, 34) ; but since 

 Stein had never encountered four, and very rarely three, gemmae upon any 

 animalcule, the idea crossed his mind that these small buds of Lagenophrys 

 might perhaps be embryos developed within the interior, and subsequently 

 discharged. Another- explanation was possible, viz. that they were animal- 

 cules which had found their way into the sheath, and were quite foreign to 

 it. However, both these hypotheses are set aside by the history of deve- 

 lopment and by the characters of the beings produced. The process consists 

 in the enlargement of the posterior extremity (XXX. 33), or of a part of the 

 side of the Lagenophrys, and the progressive detachment of the enlargement 

 as a segment or bud, and simultaneously the production of a band-like nu- 

 cleus and contractile vesicle T\ithin it. Tlus stage being so far complete, the 

 gemma does not proceed to develope into the fonn of the parent animal, but 

 self-fission takes place, and two similar ovoid bodies, each with its contractile 

 vesicle, is tlie result (XXX. 29). ^^Tien the constriction of the single gemma 

 announces approaching fi^ssion, a circlet of cilia ajipears on each side of it 

 (XXX. 34) ; and on the completion of the process, each segment has a conical 

 head surrounded with a wreath of cilia. 



From this mode of production in pairs, the number of gemmae wdthin the 

 sheath of Lagenophrys should always be two or a multiple of two ; hence, 

 when three are seen, it is to be i^resumed that one has previously made its 

 escape. From the peculiar way in which the body of the Lagenophrys is sus- 

 pended by its attached peristom to the orifice of the sheath, it is clearly im- 

 possible that anything can dii-ectly either make its entrance into or its escape 

 from the animal, without rupture, of which we have no inchcation. The way 

 in which this impediment is sm-mounted is, on Stein's authority, by the sudden 

 contraction of the body of the Lagenophrys rupturing the adhesion of the 

 peristom to the orifice of the sheath, and by its subsequent retraction within 

 it (XXX. 31). In this manner a free exit is aflforded to any contained 

 gemmae ; and after a certain time allowed for their passage, the anterior part 

 of the body again enlarges itself, and reassumes its adhesion to the sheath. 

 After their exit. Stein has no observations to show what becomes of them ; 

 but his idea seems to be that they do not produce a sheath until nearly 

 arrived at maturity, since they are so much smaller than the least of the 

 sheathed examples to be met with. 



If this account be correct, the gemmation of Lagenophrys is actually a 

 compound process of budding and fission, wliilst the resultant beings differ 

 ^ddely from those of other Vortlcellhia in all details, and are so veiy abeiTant 

 in form from the parent, that they require to undergo a metamoi^Dhosis before 

 they gain it. 



Development from Ova. Ixteexal Geems and Embetos. — Although the 

 reproduction of the Ciliated Protozoa is so largely provided for by the two 

 processes of fission and gemmation as just described, it is even more 

 marvellously so by their possession of true generative functions — a fact 

 clearly established by the latest obsen'ers, although denied by Siebold, 

 Kolliker, and others some years since, when the unicellular hypothesis 

 of Protozoic life militated against the notion of the existence of internal 

 ova or germs. Even now, indeed, Avhen we look to the researches disclosing 

 to iLS the development and discharge of germs and of living embryos, we find 

 diverse and contradictoiy statements concerning both the antecedent or pre- 

 paratory acts, and the final results. AVe cannot attempt to reconcile these 

 discrepancies, but wiU record the principal opinions of naturalists and the 

 observations on which they are based. 



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