SCIENTIFIC COMMITTEE, APRIL 22. 



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Scientific Committee, April 22, 1902. 

 Dr. M. C. Cooke in the Chair, and ten members present. 



Plants sent to the last Meeting. — Dr. M. C. Cooke reported as 

 follows : — 



"Daffodil Leaves. — I failed to find any distinct evidence of 

 bacteria in the etiolated spots, but still think that the theory of bac- 

 teriosis is probable. 



" Stem Tubers of Orchids. — Externally they exhibited rounded 

 blackish spots, beneath which the cellular tissue was blackened 

 deeply into the tuber. It had all the appearance of fungoid disease. 

 I examined it at once, but no trace of mycelium or spores could be 

 found. Kept in a damp atmosphere for fourteen days, it was then 

 examined again, with like result. I cannot account for the spots, 

 and can find not the slightest evidence that they are of fungoid 

 origin. 



" Tulip Bulbs. — The outer scales were decayed, the inner ones 

 only being sound. The decayed portions gave no indication of fungus 

 growth, and no trace of mycelium, but contained numbers of 

 nematode worms. There were also other evidences of insect depre- 

 dations. 



" Japanese Maple. — The peculiar globose pale little bodies which 

 were clustered in the axils of branches proved to be agglomerations 

 of minute fragments of woody tissue, apparently the exuviae of some 

 grub. I did not remove them to ascertain if there were any excava- 

 tions beneath, but refer them back for entomologists to examine. 



"Orchid Leaves. — There was an amorphous brown decayed 

 matter in the cells, but no mycelium or fungous spores. I attribute 

 the spots to some external cause. 



" Linum trigynum. — There was nothing on the surface of the 

 leaf, and no mycelium in the interior, and not the slightest trace 

 of fungi. All I found in the white spots was that the cells 

 were deficient in chlorophyll, just as in the Daffodil. There 

 were just the abnormal cells, but no chlorophyll in them. I have 

 often seen the same thing on leaves of the Honeysuckle, but could 

 never comprehend it. There is doubtless some physiological cause 

 for the manifestation of the disease, apparently a weakness in the 

 plant, requiring some stimulus. Is it more heat, or more nitrogen in 

 the soil ? The fact of not flowering seems to indicate weakness. I 

 can suggest nothing, only it is certain that there is no parasite at 

 present." 



"Silver-leaf^ — Mr. Worsley showed stems of Peaches with blackened 

 wood, as seen in a cross-section, indicating some condition which apparently 

 injures the whole tree, producing (or produced by) the "silver-leaf" 

 affection, which is common also on Plum trees and Portugal Laurel, but 

 it has never been accounted for. 



Tulipa sylvestris. — Mr. Worsley showed this plant, regarded as a 

 true native by Hooker in S. W. Yorks, Norfolk, Suffolk, and Somerset, 

 being naturalised elsewhere. Professor Henslow observed that it grows 



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