220 ACHLYA PROLIFERA. PAKT n. 



Tlie Achlya prolifera is also a unicellular plant, much 

 smaller than the Vaucheria, but whether an Alga or 

 a Fungus is not very clearly settled. To the naked eye 

 it appears as a cluster of colourless threads on dead 

 flies floating in water, on the gills of fishes, and some- 

 times on frogs. With a microscope the tufts are seen 

 to consist of tubes extending in all directions, filled 

 with a nearly colourless granular matter, the particles 

 of which are seen to move slowly in streams along the 

 walls of the tubes, the currents sometimes anastomosing 

 with each other. When the plant is about thirty-six 

 hours old, the endochrome begins to accumulate in the 

 dilated ends of the tubes, and is cut off from the re- 

 mainder by a transverse division,, the motion of the 

 particles being still visible in the part cut off. The 

 endochrome breaks up into a number of long masses, 

 each of which acquires a cell wall and two cilia, and 

 begins to move about within the parent cell; when 

 mature they are set free by the rupture in its wall, and 

 germinate, and produce a facsimile of the parent. It 

 appears that, in some species, the transverse dividing 

 film becomes convex as soon as the motile bodies are 

 discharged, a new fertile articulation is formed and 

 new motile spores are set free, and this process is con- 

 tinued till the vital powers of the plant are exhausted. 

 The Achlya has resting spores, which may remain long 

 in the water without change, but if a dead insect be 

 put into it, they fix on it and germinate immediately. 

 It is supposed that these resting spores are fertilized by 

 filamental bodies. The Achlya prolifera goes through 

 all its changes in an hour and a half or two hours. It 

 is found in the thermal springs at Yichy, Nevis, and 

 Yaux, where it contains an alkaline iodide. 



The whole of the plants which have been described 

 in the preceding pages belong to the group of green 

 Algse, although many are inhabitants of fresh water. 



