SCIENTIFIC COMMITTEE, SEPTEMBER 24. 



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Cattleya Gaskelliana. — Mr. Crawshay exhibited a spray of three 

 flowers, in all of which two sepals had yellow streaks occupying their 

 surface, thus slightly simulating the colouring of the labellum. 



Miltonia spectahilis. — Mr. Crawshay showed a small imported plant 

 of this genus which had not been potted for eighteen months, but had 

 sent out a flower from the terminal shoot. 



Spots on Orchid- leaves. — Mr. Crawshay read several communications 

 from Mr. Bidgood on this subject ; he has traced the spots to a fungus, 

 of which photomicrographic illustrations were shown ; but as his 

 researches were not completed, a further communication is looked for. 

 The fungus appears to be allied to GloRosporium. Dr. Cooke subsequently 

 remarked : — " Of the four leaves or bracts given me to examine only 

 one was possessed of developed pustules, the others were only leaf-stains. 

 I ascertained from the pustules on the one leaf that the fungus mischief 

 has been caused by Anthracnose, as it is called in the United States, 

 produced by some species of Gloeosporimn or Marsonia. The conidia 

 were binucleate, which may portend that when fully matured they 

 become uniseptate. The genus depends upon whether the conidia 

 become uniseptate or not. Of the four or five species of GloRospormm 

 which have been found on the leaves of Orchids, I am not yet certain 

 to which the present parasite may belong. And as the investigation 

 is already in the hands of another person who has spent a great deal 

 of time and labour in the pursuit, I do not feel that I am justified, in 

 accordance with common etiquette, in pronouncing an opinion whilst he 

 is in charge of the case." 



Schinus Molle with Fungus. — Dr. Bonavia sent leaves attacked by 

 Fumago. Mr. Pockett said that >S'. Molle was frequently grown in 

 Australia, and that it likes much warmth. In cold districts it often gets 

 black. Dr. Cooke remarked that he had no doubt the majority 

 of horticulturists have been familiar with Fumago for the past forty 

 or fifty years, at least ever since Berkeley published his paper in 

 the 4th vol. of the old '-Journal of the Royal Horticultural Society" 

 on "Moulds allied to Fumago.'" The leaves of most forest trees, 

 many evergreen shrubs, and some herbaceous plants are liable to 

 become blackened on the upper surface by something which appears to 

 be an incrustation of soot, and is known to science as Fumago. This is 

 a form of fungus growth which is superficial to the leaf, and when 

 sufficiently thick may be removed in flakes by the point of a penknife. 

 This incrustation consists of a dense interwoven network of branched 

 dark brown threads, often forming multicellular ganglia, and producing 

 chains of uniseptate conidia, resembling those common in the genus 

 Cladosporiitm, with which this was at one time associated under the name 

 of Cladosporium Fumago. Unlike that pest of the Tomato, the brown 

 mould Cladosporium fulvum, which is an endophyte, the present species 

 does not invade the tissues of the plant, and hence does it no injury, 

 except what is done by the incrustation. 



It has been remarked that this fungus when attacking the Lime, for 

 instance, almost invariably follows and establishes itself upon the " honey- 

 dew." Nevertheless, other plants suffer which are innocent of aphides or 

 honeydew. 



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