148 GE^^ERAL mSTOEY OF THE IXFrSORIA. 



undistiiigiiishable from Pohjtoma UvelJa in every material i3oint, — the absence 

 of colour, and its habitat in decomposing infusion alone offering themselves 

 as distinctive of the latter. Nay, what is more, he discovers the intimate 

 resemblance of Ghlamydomonas to the resting- stage of a Volvooc which he 

 discovered in decomposing infusions, and named V. liyalma. From these 

 considerations he concludes that Clilamydomonas and Polytoma must be ranked 

 with Volvox in the vegetable kingdom. 



But ChJamydomonas is made to appear a metamorphic condition of yet 

 other organisms. For instance, Itzigsohn states that, after the joints of the 

 filaments of Oscillaria tenuis are separated, they produce motile gonidia 

 " Avhich present in all respects the aspect of Chlamydomonads, but which, 

 after passing through many intermediate forms, grow into perfect Euglence. " 

 (J. M. S. 1854, p. 189). Likewise Hartig, in his account of the transforma- 

 tions of the Phytozoa of Antheridia (J. M. S. 1855, p. 54), makes one phase to 

 resemble Chlamydomonas destruens of Ehrenberg. Lastly, Cohn confesses 

 {On Protococmis, R. S. p. 555) that the motile or swarming form oi Protococcus 

 is scarcely distinguishable from Chlamydomonas, except that the latter has 

 not been observed by him in the ' still'' condition. But this presumed point 

 of divergence itself vanishes since Braun's observations have made us ac- 

 quainted with the quiescent phase of that organism (p. 147). 



The relation of Cldamydomonas to Stephanosphcera, and, in general, its 

 alliance with the Volvocina as a plant, have been re\dewed in the preceding 

 remarks on the family (p. 145). 



Chlamydococcus (XIX. 20-31), another unicellular, isolated organism of 

 the family Volvocina, has arrested much attention, and been described at 

 large by Flotow, Braun, Cohn, Perty, and others under the additional names 

 of Protococcus, Ha^matococms, and Hysginum. Ehrenberg has no genus 

 similarly named; but modern researches show that Gyges is in part its 

 equivalent, although but one phase of its existence. 



Ehrenberg's account of Gyyes is very meagre. He characterizes it as 

 wanting both filaments, eye, and tail, and as completely encased within its 

 lorica (an urceolus). He could discern no traces of a nutritive system, and, 

 except a very slight movement rendered e\ddent by colouring the fluid, 

 could detect no indication of animality. On the other hand, Mr. Shuttle- 

 worth examined G. sayiguineus, and stated it to have a lively motion (Edinb. 

 Phil. Journ. v. p. 29). 



In our preliminary notes on the Volvocinece in general, a vegetable nature 

 is assigned to the Chlamydococcns ; and its relation to other Volvocinece is 

 thus laid down by Cohn (A.N.H. 1852, x. p. 335) :^ 



" Chlamydococcus is a unicellular Alga in the strictest sense of the word, 

 never composed of more than one cell at any period of its growth, and each 

 division forms the commencement of a new individual, whilst the remainder 

 of the Volvocinece [i.e. excepting Chlamydomonas'] present themselves as 

 families of cells, in which a definite number of equivalent ceUs are combined, 

 in some measure, into an individual of a higher order. 



" The researches of Alex. Braun, like my own," he continues, '' have 

 proved most distinctly that Chlamydococcus can only be placed with pro- 

 priety among the Alga). It is distinguished, indeed, from the moving germ- 

 ceUs by which far the greater part of the species of Algse are propagated, both 

 by a somewhat more complex structui'e and by the circumstance that the 

 motion lasts for a very long time, and, finally, by the power of the moving 

 cells to propagate as such Avithout entering into the state of rest (germina- 

 tion) otherwise than as quite a temporary condition. But these objections 

 touch only, to some extent, the specific character of Chlamydococcus and the 



