213 



Notes on Vaucheria. 

 By M. C. Cooke, M.A., A.L.S., &c, President. 



{Read January 26th, 1883.) 



The structure and development of Vaucheria lias been so often 

 and so well studied and illustrated, that the observation of any new 

 features is quite unexpected, and will probably encounter some 

 opposition, or at least excite some doubt. One of the generally 

 accepted conclusions is, that the threads of Vaucheria are con- 

 tinuous throughout their length, only presenting septa at the time 

 of reproduction, when the short branchlets are isolated for that 

 purpose. At all events, successive septation of the main filament 

 does not appear to have been recognised by anyone who has written 

 ,upon this family. Gf its development, it is stated that "the 

 lower part of the germ cell grows out into a branched pale-coloured 

 root, and the upper part is elongated in a still more considerable 

 degree into a stem-like filament, which grows on and on by apical 

 development until its growth is finally arrested by fructification." 

 That is, in effect, the recognition of Vaucheria as unicellular. 



During the keen weather at the commencement of the present 

 winter, Mr Frederic Bates, of Leicester, collected some filaments 

 of Vaucheria from under the ice, and upon submitting them to the 

 microscope discovered that the main threads were much divided by 

 septa. He sent me portions of these threads mounted, and as 

 there was no positive evidence of the filaments belonging to 

 Vaucheria, at once I was prompted to reject his conclusion, and 

 affirm that some filaments of Cladophora must have been mixed 

 with the Vaucheria, for not only were the threads distinctly sep- 

 tate, but there was an accumulation of plasma in the cells, and an 

 appearance as of differentiation. Subsequently, however, all doubts 

 were removed, for I obtained a part of the gathering, and saw the 

 oogonia and antheridia so characteristic of Vaucheria, seated on 

 filaments which, at a short distance were septate in a similar 



Jouen. Q. M. C, Series II., No. 5. R 



