SIPHONACB^ — EEPEODUCTION OF VAUCHERIA. 315 



and these have been observed to give exit to large bodies covered 

 with a firm envelope, from which, after a time, new plants arise. 

 In the immediate neighborhood of these "capsules" are always 

 found certain other projections, which, from being usually pointed 

 and somewhat curved, have been named "horns;" and these 

 were supposed by Vaucher to fulfil the function of the anthers of 

 flowering-plants. The recent observations of Pringsheim have 

 shown that such is really the case ; for the "horns" are " anthe- 

 ridia," which, like those of the Charaoece (§ 202), produce anthero- 

 zoids in their interior; whilst the capsules are "germ-cells," 

 whose aggregate mass of endochrome is destined to become, 

 when fertilized, the primordial cell of a new generation. The 

 antherozoids, when set free from the antheridium, swarm over 

 the exterior of the capsule, and have actually been seen to pene- 

 trate its cavity, through an aperture which opportunely forms 

 in its wall, and to come into contact with the surface of its endo- 

 chrome-mass, ■ over which they difluse themselves ; there they 

 seem to undergo dissolution, their contents mingling themselves 

 with those of the germ-cell ; and the endochrome mass, which 

 had previously no proper investment of its own, soon begins to 

 form an envelope, which increases in thickness and strength, 

 until it has acquired such a density as enables it to afford a firm 

 protection to its contents. This body, possessing no power of 

 spontaneous movement, is known as a " resting-spore," in con- 

 tradistinction to the "zoospores" already described ; and it an- 

 swers the purpose of a seed, in laying the foundation for a new 

 generation, whilst the "zoospores" merely multiply the individual 

 by a process analogous to budding. The Microscopist who 

 wishes to study the development of zoospores, as well as several 

 other phenomena , of this low type of vegetation, may advanta- 

 geously have recourse to the little plant termed AchlyA prolifera, 

 which grows parasitically upon the bodies of dead flies lying in 

 the water, but also not unfrequently attaches itself to the gills ot 

 fish, and is occasionally found on the bodies of frogs. Its tufts 

 are distinguishable by the naked eye, as clusters of minute co- 

 lorless filaments ; and these are found, when examined by the 

 microscope, to be long tubes devoid of all partitions, extending 

 themselves in various directions. The tubes contain a colorless 

 slightly granular protoplasm, the particles of which are seen to 

 move slowly in streams along the walls, as in Chara, the currents 

 occasionally anastomosing with each other (Fig. 106, c). Within 

 about thirty-six hours after the first appearance of the parasite 

 on any body, the protoplasm begins to accumulate in the dilated 

 ends of the filaments, each of which is cut ofi^ from the remainder 

 by the formation of a partition ; and within this dilated cell, the 

 movement of the protoplasm continues for a time to be distin- 

 guishable. Very speedily, however, its endochrome shows the 

 appearance of being broken up into a large number of distinct 

 masses, which are at first in close contact with each other and 



