I02 



MYCOLOGY 



cate sporangial wall, which soon disappears leaving the spores on a 

 hemispheric columella. These spores are ii to 70M broad. The 300/j 

 broad zygospores are produced from similar branches of a dichotomously 

 branched zygosphore. The mycelium of the species of Thamnidium 

 enters the nutritive substratum. The large sporangia are terminal 

 while the smaller secondary sporangia are borne on lateral branches in 

 whorls below the terminal sporangium. This is typically seen in Th. 



Fig. 33. — Details of sporangia and sporangiophores of Pilobulus. i, P. micro- 

 sporus; 2, P. roridus; 3, 4, 5, P. anomalus; 6, zygospore of P. anomalus. (After 

 Brefeld.) 



elegans (Fig. 32). A related species Th. Fresenii has an upright termi- 

 nal sporangiophore, which is either sterile, or ends in a large terminal 

 sporangium, while the smaller sporangia are as in Tk. elegans. In 

 Th. amoenum, the lateral smaller sporangia are borne at the end of 

 coiled secondary sporangiophores. The secondary sporangia suffer 

 reduction in Th. chcetocladioides (Fig. 32) which in addition to having a 

 straight terminal spine-like hypha in place of the terminal sporangia has 

 some of the lateral microsporangia replaced by sterile branches. The 



