OF THE PHTTOZOA. 159 



Alga of any firm covering, and he draws a distinction in this respect between 

 Gonium and Pandorina. My observation, however, leads me to think that 

 Pandorina, as far as relates to its coat, does not substantially differ from 

 Vohox and Gonium. Besides the natiu-e of its coat, there are some other 

 points of structure in Pandorina requiring fiu'ther examination and elucida- 

 tion. Ehrenberg stated that the gonidia of Pandorina have one cilium, and 

 no eye-spot, a view adopted by Fresenius in the paper I have alluded to. 

 Focke and Dr. Braun considered Ehrenberg's observations inaccurate, and 

 Mr. Henfrey agrees with them. As far as my observations go, I should say 

 that the gonidia have usually two cilia, but that they frequently have no eye- 

 spot. Mr. Henfrey has never been able to observe a pulsating vacuole, nor 

 was any such vacuole visible in my specimens. Dr. Eresenius, on the other 

 hand, has observed one, sometimes two, such vacuoles ; and he remarks that 

 cilia and red spots are subject to considerable variation, and suggests that 

 Stephanospluera and VoJvox are probably the only distinct forms to be met 

 with in the Volvocinea'. I should protest against including Gonium pectorale in 

 the same genus as Stephanosphan^a ; but, with this exception. Dr. Eresenius's 

 suggestion is probably correct. If, however, Stcphanosijhcera and Pandorina 

 are only forms of the same plant, the generic name ' Stephanosphcera ' must 

 give place to ' Pandorina,'' the latter being of much earlier date." 



According to Braim (Kejuv., B. S. p. 21, 7iote), the colonies of Pandoinna 

 revolve always to the right ; but Prof. Henfrey corrects this statement, assert- 

 ing that they change the direction constantly. Another circumstance re- 

 marked by Braun is, that both the birth of the first generation of gonidia, 

 and the production of the succeeding generations by the division of the earlier, 

 occur in the morning after nocturnal preparation (p. 224), — a circumstance, 

 indeed, which prevails in all the Volvoclnem. We must also note that among 

 the many phases of development of Chlamydococcus pluvialis, Cohn discovers 

 two comparable in form to Pandorina Morum and to the Botryocystis Volvox 

 of Kiitzing {op. at. B. S. p. 559). 



The late valuable contribution of Mr. Carter on Eudorina {Pandorina) 

 {A. N. H. 1858, ii. p. 237) claims our especial attention as confirmatory of 

 Cohn's discovery of the sexuality of Volvox, a parallel fact to that he had pre- 

 viously made out in the case of certain indubitable Algae. Mr. Carter identi- 

 fies the organism he has studied with the Eudorina elegans, Ehr., a species 

 which natui'alists at the present day refuse to consider actually distinct from 

 Pandorina nioriim, inasmuch as the solitary character upon which the sepa- 

 ration was made by Ehrenberg, viz. the presence of a red speck in Eudorina, 

 is well known to have no pretensions to a specific, and stiU less therefore to 

 a generic character. Indeed, Mr. Carter himself treats the ' eye-spot,' if not 

 as a mere accidental feature, yet as only an adjunct of a particular phase of 

 plant-life ; for in the very paper under notice he puts forward the query, 

 '' Does not the disappearance of the eye -spot in the ' still ' form thus seem to 

 point out its analogy Avith the bright colours, especially the red, presented by 

 plants in their flowers during the season of fecimdation, rather than wdth the 

 eye of animals ? " 



We may consequently regard this excellent paper by Mr. Carter as an im- 

 portant supplement to Prof. Henfrey's admirable and lucid memoir on Pan- 

 dorina, especially its developmental histoiy. At the risk of some repetition, we 

 shaU allow the author to explain his researches and opinions in his own words, 

 and the more so as his plan of proceeding and manner of description do not 

 tally very precisely with those observed in the preceding account of Pandorina. 



" Before going," Mr. Carter writes, " to the fecundation, it is desirable that 

 we should trace the development oi Eudorina up to this point ; but not ha\ing 



