SEXUAL REPRODUCTION. 171 



they give rise to tubular or vesicular germs, which, without 

 being much elongated, produce zoospores.* 



De Bary has claimed for the oogonia in Cystopus and Perono- 

 spora a kind of fecundation which deserves mention here.f 

 These same fruits, he says, which owe their origin to sexual 

 organs, should bear the names of oogonia and antheridia, ac- 

 cording to the terminology proposed by Pringsheim for analo- 

 gous organs in the AlgaB. The formation of the oogonia, or 

 female organs, commences by the terminal or interstitial swelling 

 of the tubes of the mycelium, which increase and take the form 

 of large spherical or oboval cells, and which separate themselves 

 by septa from the tube which carries them. Their membrane 

 encloses granules of opaque protoplasm, mingled with numerous 

 bulky granules of colourless fatty matter. 



The branches of the mycelium which do not bear oogonia 

 apply their obtuse extremities against the growing oogonia ; 

 this extremity swells, and, by a transverse partition, separates 

 itself from the supporting tube. It is the antheridium, or male 

 organ, which is formed by this process ; it takes the form of an 

 obliquely clavate or obovate cellule, which 

 is always considerably smaller than the 

 oogonium, and adheres to its walls by a 

 plane or convex area. The slightly thickened 

 membrane of the antheridia encloses proto- 

 plasm which is finely granular. It is seldom 

 that more than one antheridium applies 

 itself to an oogonium. 



The two organs having together achieved FIG 98 _ Conj(lgation in 

 their development, the large granules con- perouospora , a. antkeri- 

 tained in the oogonium accumulate afc its dium - < De EarT -> 

 centre to group themselves under the form of an irregular 

 globule deprived of a proper membrane, and surrounded by a 

 bed of almost homogeneous protoplasm. This globule is the 

 gonosphere, or reproductive sphere, which, through the means of 



* De Bary, in " Annales des Sciences Naturelles" (5 me ser.), vol. v. (1866), 

 p. 343 ; Hoffmoister's "Handbook" (Fungi), cap. v. p. 155. 



t De Bary, in "Annales des Sci. Nat." (4 me ser.), vol. xx. p. 129. 



