186 THE PHENOMENON OF 



other Algse. In several of the last-named genera, an 

 active whirling motion of the gonidia occurs, even inside 

 the mother-cell, as especially in Ascidium, Hydrodictyon, 

 Clicetomorpha cerea, Sryopsis, and Cladophora ; in Ber- 

 besia, Saprolegnia, and Chytridium, on the contrary, the 

 motion does not become evident until after the birth of 

 the previously crowded germ-cells. In Phormidium, 

 Lynghya, Scytonenia, Tolpothriw, Calothrix, Mastichonema 

 (see p. 147), and other allied genera, longer or shorter 

 filiform pieces of connected, motionless gonidia are seen 

 to emerge gradually from the sheaths common to the 

 whole rows of cells, and open above, breaking-up into 

 the separate joints after they are set free. Here, as in 

 all the preceding cases, it is doubtless the elasticity of the 

 walls which effects the expulsion of the germ-cells ; the 

 bursting of the mother-cell coats is caused either by the 

 turgidity of the germ-cells, or if these do not wholly fill 

 the cavity (as in Ascidium, Hydrodiciyon, and Cladophora), 

 by increased absorption of water after previous softening 

 of the cell-membrane. We see the effect of elasticity 

 most clearly in the well-known smoke- or cloud-like 

 explosion of the spores in certain families of Fungi, espe- 

 cially in Ilehella* and Peziza,\ in which the rows of 

 eight spores are cast out with great force from the 

 clavate or fusiform parent-tubes, forming the thecal 

 membrane {hymenium) of these Pungi. 



division but by a simultaneous process, very numerous small globular germ- 

 cells, vifhich exhibit a sliarply-defined darker nucleus in the interior, and 

 possess a single very long oUium. From their want of colour, and the 

 activity of their motion, these gonidia resemble the most minute monads. 

 Their extrusion occurs either through the casting off of a lid, or through 

 mere tearing of a nipple-sliaped point. Of fifteen different species which I 

 have observed in the vicinity of Freiburg, Ch. olla is the largest, and at the 

 same time exhibits the lid-like dehiscence most beautifully; it grows on the 

 anterior wrinkled end of the bulging parent-cells of the spores oiCEdogonium 

 Landsbo'rougMi,ihe. root penetrating into the folds and attachingitself to the 

 spore. The free inflated portion of the cell is ovate, with the hd somewhat 

 thrown up at the edges and apiculated like a short nipple in the middle. 

 The germ-cells are about 3J5 millim. in diameter. 



* Vide BuUiard, ' Champignons de la France,' ii, t. 242. 



t Ibid., t. 1.54, and Corda, ' Icones Fiuigorum,' iii, t. vi, 95. (Also 

 Tulasne, 'Ann. des Sc. nat.,' 3e ser., xvii, 72.) 



