Physarum. 291 



as the older name ? I have grown it from plasmodium in large 

 quantity, and have sporangia answering both descriptions." 



The description of Physarum compressum, by Albertini and 

 Schweinitz, is as follows : " P. compressum. Stipitate, peridium 

 umbilicate, compressed like a bivalve shell, obversely parabolic, 

 grey. Stem of medium length, firm, brown. Peridium convex 

 above, dehiscing by a longitudinal fissure. Threads of capil- 

 litium rather abundant, white." Alb. and Schw., Corn. Fung., 

 p. 97. 



I am convinced that the present species is Physamm Phillipsii, 

 Balf. fil., the type specimen is in a good state of preservation, 

 and the detailed description given by the author will enable 

 any one to recognize the species. In reply to Mr. Lister's 

 question as to whether it is not the P. compressum of A. and S., 

 I must admit that I am not at all certain; the stem is not 

 brown as it should be, according to the description by the last- 

 named authors; the white capillitium, without further quali- 

 fication, is common to scores of species, therefore the only 

 feature which remains is the compressed sporangium, and this 

 I cannot admit as sufficient proof that Physarum Phillipsii 

 should be reduced to a synonym of Physarum compressum, 

 A. and S. If Mr. Lister's reasoning is sound, then we must 

 admit that pocket-lens characters are all-sufficient for the 

 determination of species, and that the more laborious and exact 

 system of microscopic examination initiated by Dr. Rostafinski 

 is a mere farce, and altogether unnecessary. In writing the 

 above I have assumed that Dr. Lister is not in possession of the 

 type specimen of Physarum compressum, A. and S. 



Physarum didermoides, Rost. (figs. 82 84). 



Sporangia elliptic-oblong, stipitate or rarely sessile, springing 

 from a Inroad, membranaceous, whitish hypothallus, wall double, 

 outer chalk-white, brittle, soon falling away; inner membran- 

 aceous, grey ; capillitium with numerous, rather large nodes 

 containing colourless granules of lime ; spores globose, brownish- 

 violet, minutely warted, the warts often arranged in lines ; 

 12 15 /u, diameter. 



