OF THE YOLVOCINA. 523 



spherical; coloiu' green or red, enclosed by a hyaline structureless mem- 

 brane, removed some distance from the coloured contents by a clear interspace 

 or areola. The central protoplasm, coloiu'ed by chlorophyll or a red oil, and 

 having one or more chlorophyll utricles at the centre, has its spherical figui^e 

 destroyed by an elongation at one part into a tapering process, from which 

 two filaments proceed, and, after perforating the external " envelope cell," 

 protrude as motile vibratile organs. The inner, coloured globule has no 

 special membrane, and in consequence imdergoes multiform transformations 

 of its outline in the com^se of development. In the resting-stage the enclosed 

 coloured mass, the '* primordial cell," secretes over its siuface, inside its enve- 

 lope cell, a new, tough, cellulose membrane, whilst the envelope cell is dissolved 

 into a mucous layer. In such still cells macrogonidia are produced by fission of 

 the contents, in the power of two, and after a time burst through the parent cell, 

 develope their two ciliary ^filaments, and proceed to develope a cellulose mem- 

 brane over their entire sui'face, which becomes further and further removed 

 until they acquii'e the characters of the ordinary moving cells. When divi- 

 sion is more frequently repeated, microgonidia are formed, which move much 

 more actively, and do not secrete an envelope cell ; they are incapable of 

 propagation, and pass immediately into the condition of rest. The motionless 

 celU of Clilamydococcus are of much simpler structui^e than the motile, and 

 consist simply of a tough, spherical, cellulose membrane, and green or red 

 contents, organized as a primordial utricle. Vacuoles are found among the 

 contents of Chlamydococcus-ceUB ; but a contractile vesicle has escaped observ- 

 ation. Chlami/dococcus and the two allied genera, Glceococcus and Chlamydo- 

 monas, differ from the true Yolvocineas in this respect : viz. they separate from 

 each other after complete fission, as primordial utricles, and then severally pro- 

 ceed to form an independent envelope cell ; whilst the rest of the Volvocinese 

 continue, on theii' production by fission, to live in groups and produce around 

 their aggregated mass an envelope cell in common. It bears the same rela- 

 tion, therefore, to the rest of the Yolvocineae that Pleurococcus does to Palmella, 

 Cijclotella to Meloseim, or Vorticella to Ejnstylis. Cldamydococcus is distin- 

 guished from the moving germs (sporozoids) by which the greater nimiber of 

 Algae propagate, 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, without entering into the 

 state of rest otherwise than as quite a temporary condition. Perty, who has 

 studied this genus veiy minutely, employs the term Hysgimim to designate 

 it, although it had previously received other names from other observers, 

 besides that we have employed. Indeed, o^ving to the various appellations 

 given, and especially the specific names invented for the multiform varieties 

 of the same organism, the synonyms became very perplexing and a positive 

 impediment to the progress of our knowledge of this genus. Among the 

 multitude of proposed species, two only are now accepted, viz. Cldamydococcus 

 pluv'mlis and Chi. nivalis; but their distinctive characters are nowhere 

 detailed in a definite and available form for our purpose. The red snow of 

 Alpine regions is the red variety of both these species. The other varieties of 

 Chlamydococcus have been more widely described under the title of Proto- 

 coccus, and those of a red colour under that of Hcematococcus. Cohn cites 

 two principal synonyms for Chi. pluvudis, viz. Hcematococcus pluvkdis and 

 Chlamydococcus versatUis, and in his Monograph on this organism employs 

 the term Protococcus pluvudis, although in a subsequent contribution he 

 adopts Braim's designation as employed by us. The many modifications of 

 form of this one species under different circumstances of development and 

 habitat have received as many diff'erent names, from the notion of their 



