INTRODUCTION. 23 



base of the aperture there issued a green sac, at first very 

 small, but which soon extended itself in such a manner that it 

 surpassed many times the length of the globule. In the 

 interior of this sac appear soon the spires, they being ac- 

 companied by their brilliant points, as in a Conjugata entirely 

 developed. The tube itself exhibits divisions, at first one, 

 afterwards two, then a great number ; at last the Conjugata 

 detaclies itself from its grain, and floats alone in the liquid, 

 and then nearly in size, and with two extremities, which are 

 still pointed, it resembles perfectly the plant which gave it 

 birth." In this description Yaucher is doubtless altogether 

 in error ; and it is difficult to conceive in what way he could 

 have been so imposed upon, a careful microscopic examination 

 of the " spore " alone being quite sufficient to convince the 

 observer that no such dehiscence as that represented by 

 Vaucher could take place. M. Decaisne * regards these 

 bodies as the true and only germs of the ConjugatcB or 

 Sunspores, as he has denominated them in removing them 

 from Agardh's extensive class of Zoospores. Mr. Jenner, an 

 indefatigable and excellent observer, writes me word that he 

 has witnessed the growth of these ^' spores," " which is, by a 

 general extension of the whole investing membrane or 

 membranes, which subsequently divides and subdivides into 

 other cells ; " and Kiitzing also, if I mistake not, states that 

 he has been a witness of their developement in Zygnema and 

 Vesiculifera, or CEdogonium. Agardli thus writes in the 

 memoir before alluded to concerning them in the Conjugata, 

 he not being acquainted with the fact of their formation in 

 the true Conferv<s: — "During the conjunction of a Conjugata, 

 one of the filaments is always giving, the other always re- 

 ceiving ; the spires of the gi\'ing filament first become 

 confused; and it is not until after the entrance of the matter 

 of tliat filament that they become irregular in the other, and 

 then the two masses become confounded together, to form 

 the elliptical or spheroidal bodies. The globules of which 

 the spires are composed do not clear themselves the one from 



* Anuules des Sciences Naturelles, Mai, 1842. 



c 4 



