LYCOGALALES 235 



i^thalia solitary or sometimes two or three together, large 2-4 cm. 

 in diameter, spherical or spheroidal, purplish-gray or brown, smooth, 

 shining ; the peridium thick, simple but in microscopic section showing 

 two or three successive layers; capillitium of abundantly branching, 

 irregular, transparent tubules, marked by numberless warts and 

 transverse rings or wrinkles, spores in mass yellowish gray, by trans- 

 mitted light, colorless, smooth or only faintly reticulate or rough- 

 ened, 5-6 yu.. 



This, one of the largest and most striking of the slime-moulds, 

 is by students generally mistaken for a puff-ball. It occurs on stumps 

 and rotten logs of various sorts in the Mississippi valley, more often 

 affecting stumps of Acer saccharinum L. The fructification, when 

 solitary, about the size of a walnut, though sometimes larger; when 

 clustered, the individuals arc smaller. The form depends largely 

 upon the place in which the fruit is formed. The plasmodic mass is 

 so large that its form is determined by gravity. Thus on the lower 

 surface of a log raised a little distance from the earth the asthalium 

 is often pyriform. This fact did not escape Micheli. See Nov. Plant. 

 Gen., Tab. 95. The Plasmodium is pale pink, soon becomes buff 

 when exposed in fruiting, finally pallid or somewhat livid, and is out- 

 wardly changed into the stout, tough peridium. This consists of an 

 intricate network of irregular gelatinous tubules enclosing within 

 the meshes protoplasmic masses of pretty uniform size, 60—100 ju,. 

 Outwardly the protoplasmic vesicles predominate; inwardly the gela- 

 tinous tubules, which arc, in some instances at least, continued to- 

 ward the centre of fructification to form the capillitium. The 

 protoplasmic masses referred to respond to ordinary stains, are often 

 broken into numberless small cells corresponding in size and appear- 

 ance to ordinary spores. 



Not common. New England, Ohio, Iowa. Perhaps more abun- 

 dant in the Mississippi valley; Canada. 



3. Lycogala exiguum Morg. 

 1893. Lycogala exiguum Morg., Jour. Cin. Soc, p. 8. 

 y^thalia small, 2-5 mm. in diameter, gregarious, globose, dark 

 brown or black, sessile, minutely scaly, irregularly dehiscent; the 



