OF THE PHYTOZOA. 141 



boscides, extend from the margin of the mouth in all the genera except Lag enella, 

 in which also, by the way, Wemeck thinks he has discerned them. Coloured 

 food has not been kno^ii to be received ; and hence the nutritive organization 

 has not been demonstrated: however, in six or seven species (nearly one -half the 

 family) internal gastric cells have been discovered. In two genera sensation is 

 exhibited by the presence of a coloui^ed spot or ocellus at the fore part of the 

 body. Multiphcation by complete division has been seen in some specimens." 



Such is Ehrenberg's account of Cryptomonadina. Dujardin has a parallel 

 family with it he names Thecamonadina, and details the following particu- 

 lars (op. cit. p. 323) : — " The Infusoria of this family having in some mea- 

 sure merely one negative character in common, viz. the non- contractility of 

 their integument, can be divided into several families accorchng to the nature 

 of the enclosing membrane and the number and disposition of their locomo- 

 tive filaments. Thus, some are globular and others leaf- like ; some have a 

 hard, as it were stony shell, whilst others are covered only by a thin flexible 

 membrane ; some, again, have but one filament, others two similar ones or 

 two of different size, and others, again, more than two. Until new observa- 

 tions have augmented the number and the knowledge of species, the diff'er- 

 cnces just pointed out will merely serve to characterize genera which are 

 indeed much more really distinct in this family than in Monadina. The 

 Thecamonadina are in fact more advanced in organization than the Monadina ; 

 they are not, like the latter, produced in artificial infusions, nor do they change 

 figure and characters according to the medium in which they exist. They 

 stand in the same relation to the Monadina that the Ehizopoda (Arcellina, or 

 Monothalamia) do to the Amoeba; : their organs are no more distinct ; but their 

 individuality is more pronounced." 



'^ The Thecamonadina are all very small, although they may be rendered 

 visible to the naked eye by their accumulation in great numbers, and by the 

 colour they then give rise to ; their colour is usually green, .... but sometimes 

 red. They are mostly cognizable by the stiffness of their body and the 

 uniformity of their movement." Dujardin ignores the stomach-sacs, the con- 

 tractile seminal vesicle, the testis, and the green ova which Ehrenberg attri- 

 buted to this family ; he likewise can assign no value to the eye- specks as 

 generic features, and is compelled to deny the occiu-rence of shells in the 

 form of a sliield, open on one side ; for those appearing so are merely flattened 

 on that aspect. He adds, the integument in all these cases is much more 

 roomy than the contents, from which it is separated by a clear space having 

 the appearance of a ring. 



Perty adopts both the terms, Cryptomonadina and Thecamonadina, to ex- 

 press the two families under which he arranges the several genera enumerated 

 by Ehrenberg and Dujardin, together with some instituted by himself. This 

 is not the place to point out the distinctions he has di^awn between the 

 two families so constructed ; but the original observations Perty has made on 

 some specimens will be of interest. For instance, he says that {op. cit. p. 81), 

 " When the green animalcule of Trypemonas volvocina (Trachelomonas vol- 

 vocina, Ehr.) is about to self-divide, it contracts itself within its glass-like 

 globular shell, oscillates to and fro, whilst the motor-fibres become lost, or 

 remain without fmiher connexion with the animal, fixed in the circular 

 opening of the outer shell. Eission now proceeds in the usual mode into 

 two and four individuals, which on their completion exhibit the red stigma, 

 p^e^dously undistingmshable among the green molecules : the breaking up 

 of the sheU, scarcely -j-cMj_th of a line in thickness, is effected either by 

 the movements of the contained beings or by dissolution." The shells of 

 Trypemonas, Chonemonas, and Cryptomonas, which contain no silex in their 



