Mr. HassalPs Notices of British Freshwater Conferva. 431 



the intermingling of the matter of two cells, which is appli- 

 cable not merely to the Zygnemata but also to true Confervae 

 ( Vesiculaspermce) and the genus Bulbochcete ; for although the 

 mixing of the endochrome of two cells be necessary, it does 

 not follow that the whole of this should go to constitute a single 

 spore in all cases, so that, consistently with the above law, 

 we may arrive at a satisfactory explanation of the juxtaposition 

 of more than two spores, by supposing, that in these compa- 

 ratively rare instances, each spore does not consist of the full 

 amount of the contents of two cells ; that where three seeds 

 are adjacent that these are made up of the matter of five cells, 

 that on either side of the terminal spore being empty ; that 

 where there are four, of the matter of six cells ; and where five, 

 the greatest number I have ever noticed, that these are con- 

 stituted by the mingling of seven cells. 



The above explanation will apply not only to the non-con- 

 jugating Zygnemata, but also to the group of Vesiculasperms, 

 where there are more than two adjacent spores, an occurrence 

 not of greater frequency than amongst the non-conjugating 

 Zygnemata. 



In one species of Zygnema w r hich I have recently met with, 

 and which is described in this paper, yoked and unyoked fila- 

 ments occur plentifully, the conjugated being however by far 

 the most abundant : the two forms of species would appear 

 to be especially related through this species. 



* Spores produced both with and without union of the filaments, 



but most frequently in the latter way. 

 Zygnema varians. Filaments of less diameter than those of 

 Zygnema infiatum, Vaucher ; cells usually four, five or six 

 times as long as broad ; spores elongated, formed either 

 with or without union of the filaments, but generally in the 

 former way, and lodged in cells, which become considerably 

 inflated for their reception ; extremities of cells inverted. 

 This species comes very close to Vaucher's Conjugata in- 

 flata, a species recently found by Mr. Jenner, but differs from 

 it in the size of its filaments, number of spires, form of the 

 inflated cells, as well as in the greater frequency with which 

 union of the filaments takes place. 



This species was first noticed by me in the vicinity of Ches- 

 hunt, since which time I have seen it amongst Confervae sent 

 by Mr. Ralfs, and within the last few days a very perfect spe- 

 cimen was forwarded to me by Mr. Jenner. 



** Spores produced by conjugation. 

 Zygnema maximum, Annals Nat. Hist, for 1842. 

 This plant appears to be subject to considerable variety. 



