VOLVOCINEiE. 277 



tion of the green cells, instead of being single, are very 

 commonly double or quadruple ; and the groups of ciliated 

 cells thus produced, form by their aggregation discoid 

 bodies, each furnished with a single cilium. These clusters 

 separate themselves from the primary sphere, and swim 

 forth freely under the forms which have been designated 

 Uvella and Syncrypta by Ehrenberg. According to Mr. 

 Carter, however, Sphcerosira is the male or spermatic 

 form of Yolvox glohator. Dr. Braxton Hicks believes that 

 he has seen the young volvox pass into an amoeboid state ; 

 he observes : — "Towards the end of autumn the endochrome 

 mass of the volvox increases to nearly double its ordinary 

 size, but instead of undergoing the usual subdivision, so 

 as to produce a maa'o-gonidium, it loses its colour and 

 regularity of form, and becomes an irregular mass of 

 colourless protoplasum, containing a number of brownish 

 granules." (Plate I. Xo. 16.) 



The final change and ultimate destination of these 

 curious amoeboid bodies have not as yet been made out ; 

 but from Dr. Hick's previous observation, made on similar 

 bodies developed from the protoplasmic contents of the 

 cells of the roots of mosses, " which in the course of two 

 hours become changed into ciliated bodies," he thinks it 

 very probable that this is designedly the way in which 

 these fragile structures are enabled to retain life, and to 

 resist all the varied external conditions, such as damp, 

 dryness, and rapid alternations of heat and cold.^ 



(1) We have had volvox under the microscope for several months, towards the 

 end of summer and throughout the autumn, and made more than a hundred 

 examinations, without having once seen the remarkable change described by 

 Dr. Hicks in the Qinirterly ,nmr. Micros. Science, vol. viii. p. 96, 1862. Never- 

 theless, as Mr. Archer observes: — "If this reasoning be correct, then contrac- 

 tility, amoeboid contractility — for I can find no more comprehensive and expre.ssiye 

 single adjective — must be accepted as an inherent quality or characteristic, 

 occasionally more or less vividly evinced, of the vegetable cell-contents, and 

 this in common with the animal ; in other words, that the nature of the proto- 

 plasm in each is similar, as has indeed, as is well known, been urged before on 

 grounds not so strong; thus reserving Siebold's doctrine, that this very con- 

 tractility formed the strongest distinction between animals and plants, as lie 

 assumed it to be present in the former and absent in the latter of the two 

 kingdoms of the organic world. Therefore, an organism whose known structural 

 affinities, and whose mode of growth and of ultimate fructification point it out 

 as truly a plant, but of which, however, certain cells may for a time assume a 

 contractile, even a locomotive, quasi-rhizopodous state, must not by any means 

 on this latter account alone be assumed as even temporarily belonging to the 

 animal kingdom, or as tending towards a mutation of its vegetable nature. 

 And from this it of course follows that an organism whose structural aflfinities 

 and reproduction are unknown, but which may possibly present an actively 



