VOLVOCINE.fi. 277 



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

 commonly double or quadruple; and the groups of flagel- 

 lated cells thus produced, form by their aggregation dis- 

 coid bodies, each furnished with a single cilium. These 

 clusters separate themselves from the primary sphere, and 

 swim forth freely from under the forms which have been 

 designated Uvella and Sfywcr^tabyEhrenberg. Accord- 

 ing to Mr. Carter, however, Sphcerosira is the male or 

 spermatic form of Volvox globator. Dr. Braxton Hicks 

 believes that he has seen the young volvox pass into an 

 amoeboid state ; he observes : " Towards the end of au- 

 tumn 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 macro-gonidium, 

 it loses its colour and regularity of form, and becomes 

 an irregular mass of colourless protoplasm, containing 

 a number of brownish granules." (Plate I. No. 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 



(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 Quarterly Jour. Micros. Science, vol. viii. p. 96, 1862. Never- 

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

 tility, amaiboid contractility for I can find no more comprehensive and expressive 

 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 befoie on 

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

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

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

 kingdoms of the org^iic 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 thia 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 affinities 

 tnd reproduction are unknown, but which may possibly present an active!?' 



