78 THE JOUKNAL OF BOTANY 



Leveille's genus Cystopus was not founded until 1847 (Ann. Sci. 

 Nat. 3rd ser. viii, p. 371). It included " Uredo Candida Pers., 

 U. cubica Mart., U. Portulacae DC, U. Bliti Bivon., U. flori- 

 formis Merat, etc." but no combinations were made. 



Meanwhile Prevost (1807) had written a remarkable paper on 

 the structure and germination of species of Uredo and similar 

 fungi. In the case of U. Portulacae he found that the spores after 

 being immersed for a time in water gave rise to zoospores — " un 

 globule immediatement suivi de trois, quatre, cinq ou six autres, 

 qui se reunissent au moment meme en un peloton, et qui se 

 meuvent quelques temps ensemble, le peloton se balan9ant ou tour- 

 nant horizontalement sur lui-meme, ou roulant dans le liquide." 

 Tulasne endeavoured to repeat the experiment but, strange to say, 

 this skilled mycologist failed, and in 1855 still placed Cystopus 

 in the Uredineae § Albuginei. Other investigators met with no 

 greater success until de Bary in 1860 (Ann. Sci. Nat. 4th ser. xiii, 

 p. 236) confirmed Prevost's results and was able to point out the 

 affinities of the genus. Three years later the same author [op. cit. 

 XX. p. 14 (1863)) records the presence of sexual organs which had 

 escaped the notice of previous observers. He revises the genus 

 {to7n. cit. p. 31) giving an account of conidia, zoospores, oogonia, 

 antheridia and oospores. Specimens with a descriptive label 

 including a description of the oospores were distributed by 

 de Bary in Eabenhorst's Fungi Europaei Exsiccata, ed. ii, ser. ii. 

 Cent. 5, 1862 {Cystopus spiimilosus n. sp. 479, C. cubicus 480, 

 C. Portulacae 481, C. candidus 482 and C. Lepigoni n. sp. 483). 



The name Cystopus was used by all mycologists until Kunze 

 (1891) in his Bevisio Generum Plantarum, ii, p. 658, revived the 

 name Albugo on the ground of priority, taking Uredo Candida 

 as the type of the genus. He used the name Cystopus for a genus 

 of Orchids : {Cystopus Blume, Orch. Archip. Ind. 82 (1858)) ; 

 most American and continental authors have adopted the generic 

 name Albugo since that time. It is clear, however, that according 

 to the Eules, Cystopus is the correct generic name as, although 

 Albugo has priority it antedates Fries' Syste7na Mycologicum 

 which is the starting-point for the nomenclature of Phycomycetes. 

 There is some difficulty when one comes to consider the names 

 to be applied to the species. If we regard the genus as beginning 

 with Leveille at least two new combinations will have to be made 

 in our five British species. As an example, the synonymy of the 

 species universally known as Cystopus {or Albugo) Portulacae msij 

 be cited : 



Uredo Portulacae DC. Fl.fr. ii. 88 (1815). 



Erysibe quadrata Wallr. Fl. crypt, germ. ii. 194 (1833). 



Uredo Candida Pers. var. Portulacearum Babenh. Kryptfl. 

 i, 13 (1844). 



" U. Portulacae DC." (under Cystopus) Lev. in Ann. Sci. 

 Nat. 3rd ser. viii, 371 (1847). 



Cystopus Portulacae de Barv in Kabenh. Fung, europ. 

 No. 481 (1862) ; Ann. Sci. Nat. 4th ser. xx, 31 (1863). 



Albugo Portulacae 0. Kuntze Bev. Gen. pi. ii, 656 (1891). 



