1899] MICROSCOPICAL JOURNAL. 32*7 



or not, thus enjoy independent existence and are capable 

 of continuing such existence for sometime, assimilating, 

 growing, and even reproducing themselves by simple fis- 

 sion, over and over again. This takes place, of course, 

 only in the presence of suitable nutrient media. Never- 

 theless the spores of many species germinate quickly 

 simply in water. A drop suspended in the form of the 

 ordinary drop culture on a cover-glass affords ample op- 

 portunity. In the course of time, usually not more than 

 two or three days, the swarm spores cease their activity, 

 lose their cilia, and come to rest, exhibiting at most noth- 

 ing more than the slow amoeboid movement first referred 

 to. In the course of two or three days more, the little 

 spores begin to assemble and flow together; at first into 

 small aggregations, then larger, until at length all have 

 blended in one large creeping protoplasmic mass to form 

 thus once again the plasmodium, or plasmodial phase with 

 which the round began. Small plasmodia may generally 

 be obtained artificially from drop cultures. Hay infu- 

 sions, infusions of rotten wood, etc., may sometimes give 

 excellent results. The spores of Didymium crustaceum 

 were sown upon a heap of leaves in autumn. An abund- 

 ant display of the same species followedin the next June ; 

 but, of course, the intervening phases were not observed. 

 The most satisfactory studies are obtained by plasmodia 

 brought in directly from the field. 



The cellulose of the Slime-mould looks toward the world 

 of plants. The aerial fructification and stipitate habit 

 of the higher forms tends in the same direction. The dis- 

 position to attach themselves to some fixed base is a curi- 

 ous characteristic of plants, more pronounced as we as- 

 cend the scale ; but by no means lacking in many of the 

 simplest, Diatoms, filamentous Algae, etc., and it is quite 

 as reasonable to call a Vorticella or Stentor, by virtue of 

 its stipitate form and habit, a plant as to call Slime-mould 

 an animal because in one stage of its history it resembles 



