CYTOLOGY OF THE MYXOMYCETES. 75 



slippery, slimy masses, sometimes nearly a foot in diameter. The 

 color is often very brilliant. For instance, in Ceratiomyxa it is 

 white, Fuligo septica yellow, Lycogala epidendrum light red and 

 Hemiirichia vesparium a beautiful dark crimson. But the color 

 is of no generic significance because different species of the same 

 genus exhibit great variability. It is to be noted that they never, 

 under any circumstances, contain chlorophyll, and in this respect 

 they differ sharply from all plants which are not saprophytic and 

 closely approximate to animals. Plasmodia are naked masses of 

 protoplasm containing abundant nuclei, but destitute of cell 

 walls, thus resembling in many ways the syncytia of higher 

 animals and large multinucleate giant cells. They apparently 

 possess all the properties of amoebae, especially the power of 

 amoeboid movement and of being actively phagocytic. They 

 engulf bacteria and foreign particles in much the same way as the 

 so-called macrophages which have been brought into prominence 

 lately in mammals through the use of vital dyes. 



In some cases, when the conditions become unfavorable, the 

 nuclei tend to clump together into larger or smaller masses which 

 encapsulate and desiccate. This resting stage, called the sclero- 

 tium, may persist for some time. On the resumption of favorable 

 conditions the envelopes are dissolved and the plasmodia re- 

 formed. 



The reproductive stages are just as remarkable. The plas- 

 modium first migrates to the upper surface of the log or stump or 

 other object, as the case may be, where it will be exposed to more 

 light. It then undergoes great and varied changes in different 

 species. It may form a cushion-like mass, an sethalium, as in 

 Fuligo; a flat vermicular aggregation called a plasmodiocarp; or 

 a number of separate sporangia as in Hemitrichia clavata. The 

 sporangia may be either sessile or elevated on pedicels. They 

 are surrounded by a definite envelope, termed the sporangium 

 wall, which may even be double. The sporangia contain spores 

 of many hues and varied sculpture and in most cases a capilli- 

 tium. The capillitium, which is composed of tubes or of threads, 

 generally arranged in the form of a network, is sometimes sup- 

 portive and may be, at the same time, concerned with the dis- 

 persal of the spores. The sporangium wall, the spore wall and 

 the capillitium are all differentiations of the plasmodium. 



