AN AQUATIC MVXOMYCETE. 77 



straight and stiff from the scarcely distinguishable ectoplasm, its very 

 fine flexible tip swaying to and fro with an irregular swinging move- 

 ment, The pseudopodia are small, numerous, and very irregular (fig. 

 17a and fig. 18). Very often the myxamceba may be seen to creep 

 forward, the flagellum in front, for a short time, and then rather 

 quickly to leave go, as it were, of the glass and subside in the drop, 

 and at once assume an elongated shape, like that of a club, and steadily 

 glide forward, suspended in the water as a "zoospore" (fig. 17b). This 

 zoospore moves with the flagellum projecting stiffly from the front 

 pointed end, where the nucleus also is situated ; the pulsating vacuole 

 appears to be always at the rounded dilated hinder end. The free swim- 

 ming zoospore-form may then come in contact with the glass surface, 

 and either assume the amoeboid form and movement at once, or wriggle 

 about with quick jerking movements (fig. Vied) for a time, and then 

 pass again into either the zoospore or the amoeboid form. The out- 

 lines figured at d for instance are sketches of the forms assumed within 

 3 minutes by the same zoospore ; while those shown in fig. 1 8 suffi- 

 ciently illustrate the passage to the amoeboid condition. 



After a certain time, however, it is noticed that a number of per- 

 fectly spherical colourless bodies (fig. 17e) are scattered about the 

 field, and as these increase in number the amoebae and zoospores 

 diminish : these spheres are encysted inyxanicebse, and indeed fig. 1 7e 

 was drawn from a specimen observed to pass over from the zoospore 

 to the amoeboid conditions (d), the latter of which then slowly rounded 

 off and assumed the encysted state. 



Before describing this and other phenomena, however, I may say a 

 few words as to the methods of culture referred to above. It is obvious 

 that absolute immunity from foreign organisms cannot be expected 

 when the sowing is made from sporangia on the submerged roots of 

 Hyacinth, and moreover it could not be supposed that the results of 

 germination could be cultivated for any length of time in distilled 

 water : nor was such the case in the examples cited above, for small 

 quantities of organic matter from the roots and of minerals from the 

 solution in which they grew were certainly added during the process 

 of sowing. . 



In order to obtain as few foreign organisms as possible, and to be at 

 least fairly certain whence they were derived, I employed the following 

 precautions. A nutritive solution (that used for growing the Hya- 

 cinths in) was prepared in a large test-tube, and a piece of fresh Hya- 



