4 Harold Thurston Cook 



s< nschaftlichen Botanik. There is some disagreement in regard to the 

 date when this name was first published. Whetzel (1904) gives the 

 third edition of Schleiden 's work (1850) as the first place and date of 

 publication; but Unger (1847), three years before the third edition was 

 published, cited this name. Although the writer has been unable to 

 consult the second German edition, which was published in 1845-46, 

 the fact that this name is in the English translation of that edition 

 but not in the first German edition, both of which have been examined, 

 indicates that it was first published in the second German edition in 

 1845-46. This is probably merely a case of mistaken identification, and 

 therefore has no standing in synonymy. The form in which Schleiden 

 wrote the specific name (in parentheses with a question mark) and 

 the fact that this name has already been applied by Persoon in 1796 

 to another fungus, occurring on the Cruciferae, indicate Schleiden 's 

 uncertainty. 



Peronospora schleideni is given by Unger, with a short Latin descrip- 

 tion of the conidial stage, in 1847. Since no mention of the perfect 

 stage is made in Unger 's paper, the name is not valid according to the 

 International Code of Nomenclature, and, furthermore, the specific 

 name of the imperfed stage is antedated by Botrytis destructor Berkeley 

 (1841). 



Peronospora destructor Caspary is the name under which the fungus 

 was listed by Berkeley in 1860, and reference was made to an earlier 

 description of the fungus by him (1841) under the name Botrytis 

 destructor. The fact that, in the generic description of Peronospora, 

 Berkeley states that this genus possesses oospores, and explains in a foot- 

 note that this generic name was adopted because of the discovery of 

 oospores, indicates that the perfect stage of the fungus was known at 

 that time. The writer has been unable to determine Berkeley's reason 

 for attributing this name to Caspary. Wilson (1914) suggested that 

 it was probably in recognition of some manuscript name. Caspary 

 1855) did publish, however, a paper in which he described the dis- 

 covery of oospores in Peronospora parasitica and other species of this 

 genus. He puts the onion-mildew fungus in the list of those species 

 which he says were seen either in the imperfect stage or not at all 

 ("Species generis Peronosporae, quas vel tantum in statu manco vel- 

 non vidi"). In listing this fungus he calls it Peronospora schleideni. 

 Possibly in a later paper he announced the discovery of oospores in the 

 onion-mildew fungus, and used the new combination which Berkeley 

 attributed to him. 



De Bary used Peronospora schleideniana Unger in listing and de- 

 scribing this species in his revision of the genus Peronospora in 1863. 

 He ffave no reason for changing the form of the specific name as it was 



