190 GENERAL HISTORY OF THE INFUSORIA. 



tion that the fibres, as a consequence of evaporation, have been broken up 

 into particles by the act of diffluence. 



Mr. Carter distinguishes certain minute colouiiess granules diffused in 

 the general protoplasm of the interior, which he specially designates " mole- 

 cules." These, says this obseiTer, are the first to appear in the homogeneous 

 sarcode, but afterwards become intermixed ^vith larger corpuscles — " gra- 

 nules" — and with " ovules ;" and by the time the o\Tiles have become fully 

 formed, the sarcode and its molecules have dried off or disappeared, " More- 

 over, in Astasia, digestive globules also appear ; but here the food is taken 

 in through a distinct mouth, while in Euglena the absence of such vesicles 

 would appear to indicate that its suj^port is of a different kind, if not intro- 

 duced in a different way." 



Ehrenberg noted the existence of a contractile vesicle at the anterior ex- 

 tremity of Euglena ; the like is also seen in Astasia ; but in neither instance 

 have its pulsations been directly obsei^ed. A nucleus is also present of a 

 discoid shape, and siuToimded, according to Mr. Carter, by a transparent 

 capsule, which appears like a narrow pellucid ring aroimd it, owing to its 

 greater size. In Chlorogonium and Amhhiopliis, Ehrenberg encoimtered 

 what he called a seminal gland, i.e. a nucleus, and, in the latter genus, men- 

 tions the presence of two wand-hke bodies in front and three behind it. 

 Thirteen such peculiar structiu'es were also seen by Perty in a large specimen 

 of Euglena sjyirogyra, which he concluded had originated from a peculiar 

 disposition of the internal substance. The same ambiguous structures are 

 doubtless referred to in the following paragi^aph by Mr. Carter, although, 

 indeed, structm-al pecuharities are detailed which would render Perty's ex- 

 planation inadmissible unless qualified in some measure {A. N. H. 1856, 

 xviii. p. 241): — ''With reference to the single, glaiiy, capsuled body which 

 exists in the centre of Phacus and in the large lip of Crumemda texta, also 

 dually in Euglena geniculata, Duj. {Spirogyra, Ehr.), on each side the nu- 

 cleus, I can state nothing further than that in the two first it consists of 

 a discoid transparent capsule, which at an early stage appears to be filled 

 with a refractive, oily-looking matter ; that it is fixed in a particular posi- 

 tion, and remains there apparently imaltered, with the exception of becoming 

 nucleated, until every part of the animalcule has perished, and nothing is 

 left but the spiral-fibre coat, and perhaps a few o^iiles. In Euglena geniculata 

 it is bacilliform, and contains a correspondingly-shaped nucleus; and al- 

 though I can state nothing respecting its uses, I cannot fail to see that it 

 has an interesting analogy, particularly in the latter instance, T\dth two 

 similar organs which are commonly seen in the Navicula, and which in 

 N. fulva, e.g., are situated in a variable position between the nucleus and 

 the extremities on either side." 



The numerous globules diffused thi^oughout the body, which, in addition to 

 the foregoing, make up the contents of the Astasicea, and according to 

 Ehrenberg are to be considered ova, have, after being denied that nature 

 by Dujardin and others, been again brought to notice under the name of 

 ovules or germ-cells by Perty and Carter. They are, in the words of the 

 latter observer (p. 223), nucleated cells, which, at an early stage, " consist of 

 a transparent capsule lined with a faint yellow film of semi-ti'ansparent 

 matter, which subsequently becoming more opaque and yellowish, also be- 

 comes more marginated and distinct, and assumes a nucleolar form.". . . . 

 " In the discoid cells of Astasia I have seldom been able to distinguish the 

 capsule from the internal contents, on account of their smallness and the 

 incessant motion of the animalcule. In Euglena, however, they are veiy 

 evident ; and it is worthy of remark, that each partakes of the form of the 



