Dt. F. Cohn on a neiv g mm of the family «/ Volvocinese. 333 



in 1849 in his essay " Ueber einzellige Pflanzen und Thiere ^* 

 (Siebold and Kolliker's Journal, vol. i. p. 270; Ann. des Sc. Nat. 

 Ser. 3. vol. xii. p. 138; Botanique, ]8i9). 

 ^^'At the same time scarcely a single botanist has hitherto ven- 

 ttired to claim as lawful pro])crty the family referred to the ve- 

 getable kingdom through Von Siebold's researches, which zoo-- 

 logists are just as little inclined to give up ; and thus even in 

 the last complete enumeration of the Algse, Kiitzing's ^ Species 

 Algarura ' has included only one single genus belonging to the 

 Volvocinecs, Botnjocystis, and this only in consequence of imper- 

 fect observation. Only a short time ago a most careful and 

 successful observer, to whom the study of the moving spores of 

 the Algse owes its first establishment and recently its very com* 

 plete elaboration, G. Thuret, has seen cause to conclude that the 

 Volvocinea, as well as the Euglena and even Tetrasporay are to 

 be regarded as animals, since they are destitute of the principal 

 character of all vegetable spores, germination (Ann. des Sc. Nat. 

 1850, Ser. 3. xiv. 214, 61 ; Recherches sur les Zoospores des 

 Algues et les Antheridies des Cryptogames). 

 "*^Only in the last it^f years has a revulsion appeared to be pre- 

 paring in this particular, since the study of the tlnicellular Plants 

 has acquired a greater extension and profundity ; and it is in 

 particular the merit of Nageli to have investigated this hitherto 

 neglected group with a criticism and a completeness of which 

 very few other families can boast (vide his ^Neuere Algensysteme,' 

 1847, and ' Gattungen einzelligen Algen/ 1849). In consequence 

 of his researches, Nageli has ventured to include at least two of 

 the forms belonging to the VolvocinecB, the genera Gonium and 

 Botryocystis, among the Algse. 



Lastly, in the past year^ the remarkable work of Alex. Braun, 

 ^'Ueber die Verjungung im Pflanzenreiche,' which contains a 

 fund of the most beautiful observations explanatory of the forms 

 standing on the limits between animals and plants, has also fully 

 recognized the notions first set up by Von Siebold on this point, 

 and included the whole family of the Volvodnece in the vegetable 

 kingdom. ^■ 



I also have been led, by a series of comparative researches, to 

 the conviction, that the assignment of the character of an animal, 

 even only of the lowest Infusorium^ depends merely on a one-sided 

 criticism of the conditions of organization ; that, on the contrary, all 

 analogy of structure and development, as well as the natural rela- 

 tionship, directly indicate to us, that the Volvocinese are to be 

 placed among plants, and indeed in the class of Alga, in these 

 again in the order of the Palmellacea, among v)hich they form a 

 special family. 



From the contradiction which this assertion has hitherto 



