290 THE PHENOMENON OF 



c. Conjugation of branched filiform cells hy club-sJiaped 

 branches, ivhich unite at their points. — The only known 

 example, is the remarkable genus of Mildew Fungi 

 Syxygites, discovered and figured with a master's hand 

 by Ehrenberg.* Erect, dichotomously branched, inar- 

 ticulate flocci, therefore unicellular filamentous little 

 plants, grow side by side in dense tufts. The uppermost 

 branches of the forks curve, like a pair of tongs, towards 

 each other, and send out (usually on the inner side of the 

 arms) clavate or pear-shaped branchlets. These fruit- 

 clubs, sometimes the opposite ones of the same fork, 

 sometimes those of different forks intermingled through 

 the social growth, unite by their apices. Ehrenberg 

 could not detect an actual anastomosis with certainty, 

 but it most probably does occur. In the middle of the 

 spindle-shaped conjugation -body thus produced, the 

 granular contents of the filaments ascend in a current 

 from both sides, and collect into a globular mass, which 

 becomes intimately combined with the membrane of the 

 middle-piece of the spindle, and shut off from the lateral 

 pieces by septa, and finally becomes free between the 

 two lateral portions, without these being torn. The 

 globular body becomes brown, and at length black, 

 during its development, and is a thick-walled cell, in 

 which, if we may put faith in Corda's figure, free 

 spores are formed, imbedded in a soft amorphous 

 mass.f 



6. Tlic conjugating cells, after dehiscence of the outer 

 membrane, unite' through the inner ; the reproductive cell 

 is formed out of the mere contents, as a new cell inside 

 the conjugation-cell. — This is undoubtedly the condition 

 in the majority of Desmidiacese. The union almost 

 always takes place between isolated cells in this family ; 

 even in the genera with the cells connected into filaments 



* 'Verhandl. der Gesellsch. iiaturforsch. Preunde zu Berlin,' 1 l)and., 

 p. 98, t. ii, iii (1829.) 



t Corda, ' Praohtflora Europaisclier Schimmelbilduiigen,' (1839,) ii. 49, 

 t. 23, 



