126 



PHYCOMYCETES. 



swarm-spores which escape from the enclosing coats and germinate 



on seedling plants. 



De Bary * found germ-tubes of 

 Cystopus entering all the stomata of 

 Zepidium sativum and of Capsella, 

 but they only developed further if 

 the part attacked were the cotyledons. 



Magnus^ observed an infection of 

 Raphanus Baphanistriim in which the 

 unopened buds were infected by swarm- 

 spores. Oogonia may be found in the 

 flowers of this same plant, whereas 

 conidia alone only are present in 

 Capsella. 



White rust is most commonly 

 observed on Capsella, causing slight 

 local swelling or marked hypertrophy. 

 It is also found to injure radish 

 {Raphanus satimis), horse radish 

 (Cochlearia arnioracia), cress (Zepidium 

 scotivum), species of cabbage and 

 turnip (Brassica Napus, B. nigra, B. 

 Eapa, B. oleracea), wall- flower (Cheir- 

 anthus Cheiri), water cress (Nasturtium 

 amphibium, etc.), caper-plant (Capparis 

 spinosa), and other wild and culti- 

 vated plants belonging to, or closely 

 allied to the Crueiferae. 



Wakker^ investigated the changes 

 brought about on a number of Cruei- 

 ferae by Cystopus. Some plants showed 

 little or no deformation or anatomical 

 alteration, others showed much. While 

 the anatomical changes in the various 

 species examined agreed in general, 

 yet some showed a predominant or 

 exclusive formation of conidia, others of oospores. The changes 



Fig. 37. — Cystopus portulacae, D. C. 

 771, mycelium ; /, basidia ; c, spores 

 with intermediate cells. (After 

 Tulasue.) 



' Morphology and Biology of the Fungi. English Editiou. 

 '' Abhand. d. botan. Vereins d. Prov. Brandenburg, xxxv. 

 ' Pringsheirn's Jahrbuck, 1892. 



