OF THE PROTOZOA. CILIATA. 339 



consider it to be a store of nutritive matter specially intended to furnish the 

 material required in the construction of the stem. 



Under the name of '^ spherical cells " Mr. Carter (op. cit. p. 124) describes 

 some special structures, which, so far as we know, are not mentioned by any 

 other observer. " They abound," he writes, " in the sarcode of Otostoma 

 (XXYIII. 2d, 26), and apparently in many of Ehrenberg's * Allotreta.' In 

 Otostoma they are of different sizes, because they are in all stages of develop- 

 ment ; and to keep up their numbers without distending the animalcule, they 

 must be continually undergoing rapid decay as well as reproduction. The 

 most remarkable feature in them is, that the largest contain, besides other 

 granular bodies, several small cells filled with a yellowish-brown fluid ; and 

 these cells are also found free among the general group ; but of what their 

 ultimate destination is, as they do not appear to grow larger, or to become re- 

 productive, we know nothing." On comparing these cells with those seen 

 in the stomachs of Planarice and Rotifera, Mr. Carter concludes that they are 

 homologous with them, and represent a biliary secreting organ. "Although," 

 he adds, " ovules may occasionally issue together with these cells from Oto- 

 stoma, &c. as well as from the Planarm, yet the two can hardly be con- 

 founded." 



On the correctness of this description we have no means of deciding : the 

 genus Otostoma has not fallen imder our observation ; and the figm^es to illus- 

 trate these spherical cells convey no clear conception of their characters. We 

 might hazard the conjecture that these supposed definite cells are only glo- 

 bides of food ; for we are scarcely prepared to admit the existence of hepatic 

 cells in the simple tissue of Protozoa, between which and the complex organ- 

 ization of Rotifera, Avith their true membranous stomach, so wide a difierence 

 subsists that no true homology can obtain. 



Perhaps the coloured " spherical cells " of Mr. Carter are identical with 

 the yelloTsish and brown vesicles Perty {op. cit. p. 53) separated from Nas- 

 sula aurea by crushing it between the glass slide and cover, from -g-jjVjj'" 

 to Y^nnr ' ^^^ ^^^®' ^^^ which he concluded to be fat-globules, and only 

 another stage of development of numerous smaller white corpuscles he met 

 with in the same being. 



Stein has established the existence of a pair of oblong or reniform soUd 

 glandular-looldng organs a little beneath the peristom of Optercularia arti- 

 culata (XXX. 20), the purpose of which cannot be surmised. Lachmann 

 has hinted at the possibility of their being nervous ganglions, but neverthe- 

 less feels quite unable to express an opinion. 



The chlorophyll-corpuscles, chiefiy confined to the soft subtegumentary 

 lamina, have already been spoken of (p. 297), and need no further notice, 

 except it be to recall an opinion of Cohn, that the coloured masses, called 

 by Ehrenberg ciliary glands, seen in a few species of Nassula, are probably 

 of the same nature as those corpuscles. 



Circulation of Contents (XXIX. 25). — The remarkable phenomenon 

 of the circulation or rotation of a portion of the contents, similar to the cy- 

 closis in the cells of many plants, is witnessed in most of the Ciliated Protozoa. 

 It had attracted the notice of several observers before Ehrenberg published 

 his great work in 1838, and was very speedily urged in argument against his 

 views of polygastric organization, to which, indeed, it seemed fatal, inasmucli 

 as such a rotation is clearly incompatible with the existence of stomachs at- 

 tached to, and connected together by, a fixed intestine. To meet the objec- 

 tion thus raised, the Berlin professor suggested that the apparent circulation 

 was abnormal, or a diseased condition, the consequence of an over- distension 

 of one stomach-sac at the sacrifice of others, an explanation quite inadmissi- 



