CONJUGATED. 131 



mata inserted in the 9th vol. of the " Annals and Magazine of 

 Natural History," p. 34. Since this paper was published I have 

 observed, in Dillwyn's " Synopsis of the British Freshwater 

 Algae," that a non-conjugating Zygnema has been described 

 accurately by Mr. Woods, under the idea of its being a variety 

 of Zygnema quininum. The accuracy of the description would 

 appear, however, to have been doubted, since we find no refer- 

 ence to the species, which is distinct, and not a variety of that 

 to which it was referred, made by subsequent writers on the 

 Alga. Mr. Harvey in his excellent " Manual " does not make 

 any mention of it. 



In these non-conjugating Zygnemata the tubes of commu- 

 nication issue from the opposed extremities of the cells, and 

 not from the centre of the sides of the cells, as in the conju- 

 gating Zygnemata. 



The analogy which exists between the conjunction of the 

 filaments of the Conjugates and the reproduction of animals 

 has led to the opinion being entertained by some that they 

 are animal and not vegetable productions. The erroneous 

 nature, however, of this view is easily proved by reference to 

 the non-conjugating species mentioned, these testifying that 

 the conjunction of the filaments is not an occurrence essential 

 to the perpetuity of the species, and that therefore no argu- 

 ments in favour of the animality of the Conjugates ought to 

 be founded on that circumstance. The union, however, 

 of distinct cells in the same filament might be regarded 

 as indicative of an animal nature ; but this view may be dis- 

 proved by reference to another genus of freshwater Alga, of 

 the vegetability of which there can be no question, viz. Vesi- 

 culifera, in which there is an union of the matter of two cells 

 in the same filament, though no tubular connection between 

 those cells. Now the analogy between the species of this 

 genus and the non-conjugating Zygnemata is too great to 

 permit of the opinion being entertained, that the former are 

 vegetables and the latter animals. 



Some have accounted for the union of the filaments by 

 supposing that the entire of one filament contained fertilizing 

 and the other fertilizable material ; but this view is like- 

 wise shown to be erroneous by the occurrence of non-con- 

 ic 2 



