Sheldon: a study of some Minnesota mycetozoa. 463 



bulinaand allied species, i Durand has observed the germination 

 of the spores and subsequent fusion of the swarm-cells of En- 

 teridium.2 But it is to Lister that we are indebted for knowl- 

 edge of the development of the Plasmodium. In his paper on 

 Badhamia and Brefeldia,'^ and in his later paper on the divis- 

 ion of nuclei in the Mycetezoa,* this author has set forth the 

 recently discovered facts regarding the physiology and morph- 

 ology of the multi-nuclear Plasmodium. 



Sooner or later this form heaps itself up and becomes trans- 

 formed into the fruiting or sporangial stage in which it is most 

 commonly found. The shape of the individual sporangium 

 varies greatly, although it is usually constant for a given 

 species. It may form a flat cake like mass or aethalium as in 

 Lycogala or Puligo. The latter is very abundantly distributed 

 and is commonly known' as the flower of tan. In other cases 

 the Plasmodium may be transformed into a net. One species 

 which takes this form is Hemiarcyria serpula. Or the mass may 

 break up into globose or irregularly- shaped heaps which are 

 sessile on the substratum, as in Trichia inconspicuaor Diderma 

 globosa. The latter species belongs to a group which is char- 

 acterized by the presence of minute crystals of carbonate of 

 lime. The presence or absence of such crystals is a useful 

 character in grouping the genera of these organisms. Some- 

 times these tiny globose masses are lifted on slender stalks 

 which rest upon a common residue of the protoplasm beneath 

 them; this is usually termed the hypothallus. This is seen in 

 such forms as Dictydium, Stemonitis, Clathrodes, Lampro 

 derma and Cribraria. Other forms which in the plasmodial 

 stage are often noticed as spittle- like masses clinging to stems 

 of grasses and other meadow plants, are transformed into a 

 white, fluffy, feathery, fragile mass as in Mucilago. 



The color of the little sporangia, of their tiny stems and of the 

 hypothallus beneath them is as various as the colors when in 

 the plasmodial state. The sporangium is found to contain 

 numerous spores and with these occur other modified portions 

 of protoplasm in the form of elaters or capillitial threads which 

 vary much in shape, external markings and color in the differ- 

 ent species. 



(1) Rex. Geo. A. Bot. Gaz. 15:315. 1890. 



(2) Durand. E. J. Bot. Gaz. 19:89. 1894. 



(3) Lister, Arthur, Aan. Bot. a:l. 1888. 



(4) Lister, Arthur, Journ. Linn. Soc. Bot. 29:529. 1893. 



