52 



THE MYXOMYCETES 



tion has been studied by Harper and Dodge (1914) and by Bisby 

 ( 1914) , among others. True capillitium in Fhysarella mirabilis and 

 Stemonitis jiisca [Bisby (1914)] arises during sporangia! cleav- 

 as^e among tubular spaces formed from invaginations. The 

 plasma membrane lining these spaces progressively deposits sub- 



FiG. 13. Plamiodiopbora brassicae. A. Young plasmodia within root hair. 

 B. Mass of spores that have come from mature plasmodium. C. Stages in 

 germination of spores and escape of myxamoebae. {A and B after Chupp, 



C after Woronin.) 



stance that becomes the walls of capillitial threads. In S. fiisca 

 these threads are continuous with the sporangial wall and with 

 the columella. Some genera, such as Enteridium and Lycogala, 

 form pseudocapillitia, which are products of protoplasmic de- 

 generation. 



In Comatrichia and Lamproderma the capillitium, as in Stemo- 

 nitis, is continuous with the columella. In Hemitrichia and 

 Arcyria the capillitial threads are elaborately provided with 

 spines and spiral thickenings. In Badhamia there is a network of 

 lime-containing tubes; in Phvsarum the lime is aggregated into 



