THE MYXOMYCfiTES. 99 



Lastly, it may be objected that the power of amoeboid movement 

 IS characteristic of animal organisms. But, here again, the Volvociueae 

 come to our aid. Archer, in 1862, observed the primordial cells of 

 Stephanosphaera (an Alga allied to Volvox) leave the hyaline sphere in 

 which they are usually contained, and move about the field exactly in 

 the manner of a green Amoeba.* In fact, although they moved, like 

 Amcjeba, by extensions and retractions of pseudopodia, they went so fast 

 that they might have given even LitluDiimha discus fifty micro-milli- 

 meters start out of a hundred, and yet have won the race. Various other 

 cases of the same kind are recorded among mosses, algis, fungi, etc.,t and 

 Sachs instances the amoeba-like movement of the protoplasm which 

 escapes from a ruptured cell of Vaucheria, as similar in its character. J 



We left our Myxomycete in an amoeboid form, creeping over the 

 matrix upon which it grew, increasing by fission, and feeding perhaps 

 upon the bacteria and other organised substances in the fluid. In this 

 state it has received the name of Myxamoeba. Where one spore has 

 germinated there will probably be many more, and these, creeping 

 about, meet and unite wiLh one another in gradually increasing 

 numbers, and at last form a mass, technically known as a plasmodium, 

 which is relatively of colossal size, and which creeps about in a 

 reticulate manner over the matrix. g It sends out pseudopodia in 

 various directions, and retracts them again, just like a gigantic amoeba 

 or some species of Foraminifera. 



Moreover this plasmodium consists of an outer denser transparent 

 layer not containing granules, and an inner granular mass in which 

 are embedded a number of contractile vesicles derived from the 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 reticulated 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 upwards 

 of the form of the future sporangia. It then forms a firm 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 



* " Quarterly Journal of Microscoincal Science," 18G5, pp. IIG, 185. 



+ " Quarterly Journal of Microscopical Sciouce," 18G2, pp. 'JG-103. 



; Sachs' Botauy, p. 41. 



§ I have seen a plasuiodium of Phijsaruin ciiiereuin, I'oriuing a patch of jelly- 

 like substance nearly as large as one's hand, which roamed about the surface of a 

 rotten stump for three weeks, and finally retreating to the base formed its 

 sporangia in a few hours. In a day or two the sporangia were ripe and dehisced, 

 iiikl iu a week nothing was left but Ihoir bleached and empty bases. 



