184 THE PHENOMENON OF 



(see p. 177) ; by breaking through the back-wall of the 

 cell of a creeping filament in Apkanockcete repens.* I 

 have observed four active germ-cells expelled through a 

 breaking across of the mother-cell exactly in the middle 

 in Conferva bombycina ;f J Agardh likewise saw four 

 active gonidia emerge from the cells of Enteromorpha 

 dathrata ;} 4, 8, or 16 break out laterally, in the way 

 described above (pp. 148, 161), from the parent-cell of 

 Ulothrix zonata. Chlamidococcus pluvialis (pp. 138, 

 158) may be mentioned again here. Four (rarely two or 

 eight) active cells emerge from the thick-coated, resting 

 (seed-) cells by irregular dehiscence of the cell-membrane, 

 during which operation the innermost extremely delicate 

 layer of the mother- cell membrane becomes detached, 

 partially emerging as a vesicle, and tearing subsequently 

 to the outer thick cell -membrane. The gonidium-like 

 cells gradually produce an extremely delicate membrane 

 over themselves in the way above described, inside which 

 they finally divide again into 4 (rarely 2 or 8) parts, 

 or, when the formation of microgonidia takes place, into 

 32 parts, which begin to move about inside the roomy 

 coat even before they swarm out. In Pediastrum (p. 161) 

 4, 8, 16, 32, or 64 active gonidia, enclosed by the 

 vesicular inner layer of the mother-cell, break out by a 

 tear in the old cell. A larger number of active gonidia, 



* Aphanocheete is a new genus of Algae, which perhaps will have to be 

 united with Herposteiron, (Kz., ' Sp. Alg.,' p. 424,) from which it differs 

 through the absence of the vertical torulose branches. The bristles, which 

 frequently spring from the back of the cells, are not sheathed, as in 

 Coleochcete, yet articulated in the upper part, but at the same time so 

 delicate that the upper portion is difficult to make out. The formation of 

 the pairs of germ-cells takes place by division parallel to the septa. The 

 germ-cells are nearly globular,' possessing two cilia. A. repens occurs not 

 unfrequently near Freiburg, particularly on (Edogonia, Vcmcheri^ Mcngeotia, 

 Siroyonium, Conferva, &c. I observed the swarming of the germ-cells in 

 August,, 1847. t 



f Observed in October, 1847- It is remarkable that the formation of the 

 germ cells of this very common Conferva has been but seldom observed. 



% 'Ann. des Sc. nat.,' 1846, p. 199, t. xii, f. 6. According to Thuret, 

 ('Ann. des Sc. nat.,' 1845, p. 274), the gonidia of Ulva and Enteromorpha 

 possess four cilia. 



