3l36 GENERAL HTSTOEY OF THE INFUSOEIA. 



multiplied. Theii' minuteness is a bar to observation ; and it is only by the 

 concurrence of favourable circumstances — by the presence of the ovules in 

 their first, intermediate, and finished stages — that they can be satisfactorily 

 made out, as in Nassula aurea, Euglena viridis, CTionemonas bicoJor, &c. 

 Fission may be several times repeated ; but the formation of germs takes place 

 at the expense of the contents of the parent. 



The unusually small size of many animalcules is another argument advanced 

 in favour of propagation by germs or ova, since the act of fission is limited to 

 a certain size, and the natural characters of the species are to be preserved. 

 Thus Pertymet with examples of Kerona pustulata as small as 1-70'", which 

 could scarcely originate from fission. They were exactly like the original 

 animalcule except in being more round. Specimens of Pleuronema crassum 

 occur no larger than 1-90'", devoid of molecules, more transparent and slender 

 than old ones, with a more pointed apex, but otherwise their coimterpart. 

 Again, Nassula aurea varies from 1-150'" to 1-12'" ; and in those of 1-50'" the 

 rudiments of the " dental" apparatus are distinguishable. AiiAmpliileptus mo- 

 niliger, 1-6'", having a very short neck, was distended by 100-150 germs or 

 ovules surrounded by some thousands of fine moL ijules ; that these were neither 

 vacuoles nor stomach-sacs was seen at places where they displayed themselves 

 as individualized corpuscles. Moreover there were no other animalcules or par- 

 ticles of food in the glass containing the AmpMleptiis, and aU the germs were 

 uniform in size, in hue, and in refractibihty, and readily distinguishable from 

 some swallowed Infusoria present in some spots. The green spheroidal cor- 

 puscles in Paramecium versutmn, having a medium size of 1-450'", are true 

 ovules: they do not change colour, like the green nutritive matters of Infusoiia, 

 to yeUow, red, or brown ; and when the animalcule is left dry by evaporation, 

 they become isolated. Although no germinal speck is discoverable in these 

 bodies as in ordinary ovules, yet it is remarkable that a fold, streak, or darker 

 space is visible. Small specimens of this Infusorium also occur in wliich the 

 ovules are colourless or pale green ; and on one occasion Perty saw, amid the 

 fully- developed individuals, oval greenish animalcules of about 1-60'", which 

 seemed no other than the escaped germs of the Paramecium. 



Such are some of the principal observations Perty appeals to in order to 

 substantiate his hypothesis of internal germs and of development from them. 

 He has given, in illustration, a number of figures ; but they are too rudely 

 dra^\T:i to efficiently answer their object ; and we must confess our inability to 

 receive the fact of the existence of ova or germs as at all demonstrated m the 

 CiHata either by the researches of Mr. Carter or of Perty. The discoid or 

 globular nucleated cells which the first-named writer makes out so clearly in 

 the Astasicea, are merely supposed to be represented by certain " defined glo- 

 bular bodies of nearly equal size and of a faint opaque yeUow colour^ which 

 closely resemble ovules " (why ?), not uncommon in many ciliated Protozoa, 

 e. g. '^Amphileptus fasciola, Himantophorus Charon, &c." Such evidence is 

 purely presumptive, and is little aided by M. Jules Haime's anomalous obser- 

 vations. Respecting Perty's arguments and reported phenomena, it may be 

 objected that he does not estabLLshhis attempted rigorous description of germs 

 — does not show their distinctive peculiarities as stated, and seems to have 

 confounded together various internal bodies in his description of germs. Thus 

 in the Paramecium versutum (which he presumes to be the same animalcule 

 described by Colin as Loxocles Bursaiia) the green spheroidal corpuscles 

 look to be nothing more than the chlorophyll globiiles pointed out by 

 Cohn and Stein. Again, of the ambiguous corpuscles in other Protozoa cited 

 as ovules or germs, it is simply from their doubtful character that this 

 can be presumed ; for our knowledge of the contents of the Ciliata, of the 



