172 FUNGI. 



fecundation, should become the reproductive body, vegetable 

 egg, or oospore. The gonosphere having been formed, the 

 antheridium shoots out from the centre of its face, close against 

 the oogonium, a straight tube, which perforates the walls of 

 the female cell, and traversing the protoplasm of its periphery, 

 directs itself to the gonosphere. It ceases to elongate itself 

 as soon as it touches it, and the gonosphere becomes clothed 

 with a membrane of cellulose, and takes a regular spheroidal 

 form. 



Considering the great resemblance of these organs with the 

 sexual organs of the Saprolegnise, which 

 are closely allied to the Algae, and of 

 which the sexuality has been proved, 

 De Bary adds, we have no doubt what- 

 ever that the phenomena just described 

 represent an act of fecundation, and 



P.O. ss.-Antheridia and that the tube pushed out by the anthe- 

 oogonium of Peronospora. (De ridium should be regarded as a fecun- 

 dating tube. It is remarkable that 



amongst these fungi the tube projected by the antheridium 

 effects fecundation only by contact. Its extremity never opens, 

 and we never find antherozoids ; on the contrary, the anthe- 

 ridium presents, up to the maturity of the oospore, the appear- 

 ance which it presented at the moment of fecundation. 



The primitive membrane of the oospore, at first very thin, 

 soon acquires a more sensible thickness, and becomes surrounded 

 by an external layer (epospore), which is formed at the expense 

 of the protoplasm of the periphery. This disappears in propor- 

 tion as the epispore attains maturity, and finally there only re- 

 mains a quantity of granules, suspended in a transparent watery 

 fluid. At the period of maturity, the epispore is a slightly thick- 

 ened, resistant membrane, of a yellowish-brown colour, and finely 

 punctate. The surface is almost always provided with brownish 

 warts, which are large and obtuse, sometimes isolated, and some- 

 times confluent, forming irregular crests. These warts are com- 

 posed of cellulose, which reagents colour of a deep blue, whilst 

 the membrane which bears them preserves its primitive colour. 



