94 THE MYXOMYCETES. 



are embedded a number of contractile vesicles derived from tbe units 

 of which the mass was formed. The plasmodium is continually 

 moving while the conditions are favourable : those of the larger species 

 can creep some distance and ascend bushes and plants. A distinct 

 circulation or cyclosis can be observed in the contents, a streaming 

 motion of the protoplasm, like that of Nitella, but more resembling 

 the motion of the I'eticulated protoplasm of the Foraminifera, as in 

 Gromia and Labyrinthula. 



Should the conditions become unfavourable, this plasmodium will 

 pass into an encysted or resting stage, but if they continue suitable, 

 the net-work begins to contract and to put forth outgrowths iipwards 

 of the form of the fiiture sporangia. It then forms a tirm membrane 

 on the outside, usually without any trace of structure, while the 

 enclosed mass proceeds to resolve itself into spores by free cell 

 formation. If the sporangium is to contain threads, part of the 

 protoplasm collects into stringy filaments. The lime is crystallised 

 out, either in the wall of the sporangium or in the capillitium, or in 

 both, and the water is expelled or evaporates. This process takes 

 place very quickly, and thus the cycle of development is completed. 



In a few instances, as in Enerthenema and Ophiotheca, the spores 

 are described as being attached to the threads, but it is probable that 

 this is a mistake, and that the spores are really always free, being 

 formed like those of the Ascomycetes. Certainly I could find no trace 

 of their attachment in any specimen of Enerthenema which I have 

 examined.* It will be seen that, in this formation of the spores by 

 endogenous division, the Myxomycetes differ essentially from the 

 Trichogastres and the Nidulariacei, between which they are placed in 

 Berkeley's classification, as well as frona the other Gastromycetes, in 

 which the spores are always borne upon sporophores, just as in the 

 higher gi'oup. 



It is but just to say that the foregoing account of the germination 

 of the spores is not uncontradicted. Both Berkeley and Currey t 

 mention having observed the spore of a Myxomycete germinate in the 

 ordinary way by the emission of a hyphal filament ; but we maj' more 

 easily suppose that in these cases the spore of some extraneous species 

 was accidentally present than that all other observers are wrong, or 

 that both methods of germination are possible. Van Tieghem has 

 recently described a modification of the process related above, where 

 the myxamcebEe, instead of forming a plasmodium in which the units 

 of which it is composed are undistinguishable, remain completely 

 independent though aggregated together, each forming itself into 

 a single spore with a cellulose coat.j 



* Dr. Quelet has recently asserted that the spores of all species are borne ou 

 the threads as sporophores, apparently on his own authority. But then he 

 also calls the plasmodium by the totally inappropriate name of mycelium — 

 -J. de Photo, et de Micro.," 1881, translated in " Northern JUicroscopist," 

 March, 1882. 



+ " Transactions of the Linnwau Society." xxiv., p. 156. 



; Van Tieghem, " Bull. Soc. Bot. France," xxvii., pp. ai7— 22. 



