434 J. SLADE ON MYCETOZOA. 



general study. When in 1829 Fries first defined the group, he 

 named it Myxogastres, and this name has been adopted by Mr. 

 Massee. Walroth, who followed Fries, called it Myxomycetes, 

 deeming it more akin to vegetable life ; and he has been followed 

 by Sachs in his " Text Book of Botany," and Kerner in his 

 " Natural History of Plants." De Bary, thinking it had more 

 affinity with animals, termed it Mycetozoa, and he has been 

 followed by Lister. 



The three specimens of this group which were exhibited at 

 the Soiree, and which I will now describe, are set forth in 

 the diagrams. They illustrate three well-marked genera — viz., 

 Arcyria, Stemonites, Trichia. It is well to remember that in 

 illustrations of these or other genera, whether in microscopic 

 preparation, drawing, or diagram, only one phase in the life- 

 history of each is represented, namely the fruiting stage. They 

 are all Sporangia, and it is only at this stage they present 

 characters sufficiently definite for purposes of classification. 



In Arcyria we see a stalked capsule. At first it is closed, but 

 when ripe it bursts ; the top part is blown away, the bottom 

 remains as a cup, to which are attached quite a cloud of threads. 

 This is the capillitium, and encloses numberless spores. When 

 highly magnified, each fibre of the capillitium is seen adorned 

 with rings, half-rings, knobs, warts, etc. 



In Stemonites the capsule is stalked ; the stalk continues into 

 a columella, from which branches the capillitium ; the branches 

 become finer and finer, ultimately uniting to form a beautiful 

 network enclosing the spores ; the whole being covered by a 

 delicate membrane, which, when ripe, ruptures, entirely dis- 

 appears, and is so said to be evanescent. 



In Trichia the sporange is a simple sessile capsule, which when 

 ripe bursts and exposes a dense mass of threads — the capillitium — 

 each thread of which is detached, unbranched, tapering at either 

 end, and over it traverse well-marked spiral bands. As in the other 

 examples, spores are abundantly scattered through the capillitium. 

 For the many beautiful forms assumed by sporangia of other 

 genera I must refer you to the plates from Mr. Massee's mono- 

 graph laid out for your inspection. 



The capillitium, or system of threads, forming a scaffolding 

 among the spores, is present in most genera. It is best de- 

 veloped in Arcyria and Trichia. 



