50 THE MYCETOZOA 



although the reaction of the plasmodium as a whole is alkaline 

 (Metschnikoff, 19). Pepsine, the presence of which in plasmodia of 

 Fuligo was shown by Krukenberg (12), is doubtless the agent by 

 which, acting in this acid medium, the digestion is brought about. 



Raw starch grains which had been ingested were found to pass 

 unaltered through the plasmodium of Badhamia utricularis, though 

 grains which had been previously swollen in warm water were 

 digested (14). 



The plasmodium of this species at any rate has the power of 

 dissolving cellulose. This is evident from the nature of its food, 

 and has also been directly observed (14) when a plasmodium was 

 seen to extend over the hyphae of a mould. The cellular walls of 

 the hyphae were dissolved " like sugar in hot water " as soon as the 

 hyaline border of the plasmodium reached them. 



The Sclerotium Condition. As in the earlier phases of the life- 

 history, a passive condition may, as we have seen, be assumed in 

 the plasmodium stage, the protoplasmic mass breaking up into 

 cysts and assuming as a whole a firm consistence. To this con- 

 dition de Bary gave the name Sclerotium. As it supervenes, 

 the streaming movements gradually cease, foreign bodies are 

 extruded, and the plasmodium becomes separated into distinct 



masses, each of which contains 10-20 

 nuclei, and secretes a membranous cyst- 

 wall. 



The assumption of the sclerotium 

 condition is readily induced by allowing 

 plasmodia to dry, and when so treated 

 they assume a firmer and firmer con- 

 sistency, until the masses of cysts attain 

 a hard and horn-like condition, in which 



Part of a section of the plas- . 



medium of Sadkamia utricularis vitality may be preserved for as many 



when passing into the sclerotium ,-, c, , , 



condition, x 310. , a nucleus, as three years. Sclerotium cysts may, 



however, be formed in water, but the 



conditions under which this occurs are obscure. When the dry 

 sclerotia are placed in water the protoplasmic masses absorb or 

 break through the cyst-walls, fuse together, and the active plas- 

 modial condition is resumed. The revival occurs in a few hours. 



It is to be noted that the unit represented by the sclerotial 

 cyst is different from the microcyst of the preceding stages, which 

 was uninucleate, and also from the sporangium of the succeeding 

 stage, which is much larger, and contains a much greater number of 

 nuclei. 



(d) The Formation of Sporangia. 



The conditions under which plasmodia pass into the succeed- 

 ing phase, that of spore-production, are in part obscure, but one 



