44 JOUKNAL OF THE KOYAL HORTICULTURAL SOCIETY. 



Kissling* states that not only is the general aspect and size of 

 Botrytis modified by the particular substratum on which it is grown, but 

 that the functional acti\dty of the conidia is also affected. The last- 

 named author gives an excellent resume of what has been done with the 

 parasitic species of Botrytis and Sclerotinia. 



Botrytis cinerea, Pers., is exceedingly common as a saprophyte on 

 decaying vegetable matter, and it has been proved possible to educate, as 

 it were, by a series of cultures these wild saprophytic forms to become 

 true parasites ; in fact, the members of the Polyactis section of Botrytis 

 appear to be capable of living as saprophytes or parasites depending on 

 circumstances, thus coming under De Bary's category of facultative 

 parasites. This power differs in degree in different species. Bearing on 

 this point Marshall Ward, in his admirable study " A Lily Disease, ""^ 

 states : " Accepting De Bary's results with Peziza sclerotiontm, I regard 

 his fungus as a form physiologically midway between the ordinary 

 saprophytic Pezizas, and my imrasitic one ; in other words, De Bary's 

 fungus is in process of being educated to imrasitic habits ! " 



I have observed that the excrementa of minute insects which so fre- 

 quently abound amongst patches of mould often consists almost entirely of 

 Botrytis conidia, and that many of these conidia germinate readily and 

 produce a myceliun quite as vigorous as that formed by conidia that ha^■e 

 not undergone such an ordeal. It is quite probable that these minute 

 creatures may in a measure assist in the diffusion of the fungus. 



No trace of an ascigerous condition of the Botrytis has been observed 

 during numerous experiments extending over five years, although hundreds 

 of sclerotia developing and hybernating under very varied conditions have 

 been constantly under observaiion. If there is, in reality, a genetic 

 relationship between Botrytis and Sclerotinia it must be very slender 

 indeed at the present day. As already stated, De Bary is responsible for 

 this idea, but perhaps he only intended the bald statement, unsupported 

 by any account of direct cultural experiments as was his wont when such 

 evidence existed, as a suggestion rather than as a proved fact. Soraeuri 

 and Frank § also furnish circumstantial evidence as to the relationship 

 between Botrytis and Sclerotinia, but the crucial test, which once for all 

 would settle what appears to be as yet an open question, the production 

 by means of pure cultures of the Sclerotinia form from a Botrytis 

 conidium, and the converse, remains yet to be accomplished. The 

 consecutive appearance of Botrytis and Sclerotinia in large masses of 

 tissue is suggestive but not convincing. It is somewhat significant that 

 where an undoubted genetic relationship between Sclerotinia and a 

 conidial form has been demonstrated, as by Woronin, || the conidial form 

 is not a Botrytis. 



Smith, ^ an American mycologist, after years of investigation, has come 

 to the . conclusion that Botrytis &nd Sclerotinia are not phases of the 

 same species, but that they are entities respectively, agreeing in producing 

 sclerotia similar in appearance and structure ; and furthermore, both under 



* TIedwigia, 1889, p. 227. f ^nn- Bot. ii. 1888, p. 319. 



X Hanclh. cUr Pflanzenkr. ii. p. 249. § Die Krankheiten dcr Pflanzcn, p. 530. 



II Mini. Acad. Imp. St. Petcrsbourg, ser. vii. vol. xxxvi. 1888. 



t Bot. Gaz. xix. p. 369 (1900). 



