200 



Genus 68. Pulysaccum. D.C. 

 Common peridium simple, rigid, bursting irregularly ; internal 



mass divided into distinct cells, filled with peridiola ; spores 



mixed with threads. 



Polysaccum olivaceum, Fr. This fungus does not seem to have 

 been found in Great Britain since the time of Sowerby, whose 

 specimen, figured in English Fungi, was obtained at Highgate. It 

 is common in the south of Europe. The peridiola which occupy the 

 cells into which the common peridium is divided can be easily 

 removed from their positions. Vittadini here, as in Scleroderma, 

 regards the " sporidia as included in one-spored sacs in the early 

 stage," and probably, from a like erroneous view of the granular 

 contents of the spores. Corda describes the structure of this curious 

 fungus thus in his " Icones," " The common peridium is constituted 

 of several peripherical layers, formed by the abortion of the 

 sporangiola occupying the cells of the substance of the fungus, 

 which constitutes the septa, these void cells are pressed upon one 

 another in layers, forming the many-coated common peridium. 

 The sporangiola are arranged irregularly, and commonly singly, 

 in each cell of the mass of the fungus ; the cell walls, at first full 

 of juice and moist, become at length dry and brittle, they are 

 continuous with each other, but not with the sporangiola. Each- 

 sporangiolum consists of an outer, delicate, floccose, at length 

 papyraceous membrane, which, in a section, can be easily seen to be 

 distinct. In the early state the coat of the sporangiolum, together 

 with its contents, forms a fleshy, moist, homogeneous substance, 

 which afterwards divides itself into an external envelope and a mass 

 of spores mixed with threads." The genus Polysaccum seems to be 

 a compound Lycoperdon, according to the history of its structure 

 and development which we have been considering. It would be 

 interesting to meet with this plant once more after so long a period 

 of its absence from our flora. M. Tulasne gives an account of the 

 structure of Polysaccum in the " Annales des Sciences," ser. ii., 

 vol. 18, p. 133. He says, "if a thin slice of a sporangiolum be 

 placed in the microscope one sees that the threads which it contains 

 are generally terminated by globose, or ovate, cells larger than the 

 other cells ; if the sporangiolum is young these ceUs are smooth 



