SCIENTIFIC COMMITTEE, OCTOBER 15. 



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SCIENTIFIC COMMITTEE. 



October 15, 1901. 



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



Mr. J. Masters Hillier, visitor. 



HaiutJwrn Shoots, dead. — Mr. Saunders reported as follows upon the 

 specimens sent to the last meeting, exhibited by the Rev. W. Wilks : — 

 " The bark of the shoots in places was splitting, and had all the appear- 

 ance of being attacked by canker ; but there were no signs of any fungus 

 on examination with a strong pocket lens ; under the bark were several 

 small orange-coloured dipterous grubs, belonging to the family Cecido- 

 myidcB. They exactly resembled grubs which I have found feeding on 

 the ' Rose-rust,' Phragmidium sicbcorticum, and the ' Bean-rust,' Uromyccs 

 fahce, and I cannot help thinking that they must have fed on some fungoid 

 matter. Their mouths are not suited for feeding on any hard substance, 

 such as the Hawthorn shoot, which was practically dead. What may 

 have caused the death of the shoots I cannot say, but I should suggest 

 that it was of fungoid origin." 



Cucumber disease. — Mr. Houston described a disease which is doing 

 much injury in parts of England, one grower alone having lost £1,000 

 worth of fruit. It appears on the plants twelve weeks after sowing the 

 seed. The fungus is Gercospora melonis, M.C.C., described by Dr. Cooke 

 in 1896. It begins with a few spots on the leaves, spreading till there is 

 no healthy leaf left. As the spores are multiseptate, and each joint can 

 propagate the fungus, the disease is easily communicated to other plants. 

 There is no remedy except complete destruction. Cucumbers or Melons 

 should not be grown in the same pits in which diseased plants have been 

 for some seasons. 



Pelargonium-leaf striking root. — Mr. Houston also showed a leaf of 

 the Ivy-leaved species, of which the petiole had formed a callus with 

 numerous roots. The effect upon the blade was to enlarge the cells. 

 Professor Henslow observed that he had read of, but could not recall the 

 reference to, a very similar result occurring with a leaf of Ivy, which, 

 however, became much enlarged. 



Acacia armata seedling. — Mr. Holmes exhibited a specimen having all 

 the leaflets well developed from the first. At a subsequent stage, only 

 phyllodes are borne by the tree. 



Galls on Beech-leaves. — Mr. Holmes showed specimens remarkable 

 for their hairiness, while the leaf of the Beech is perfectly hairless. 

 Professor Henslow observed that this was a common result in galls on 

 many plants. He had observed it on the smooth-leaved Erica scoparia, 

 which bore hairy galls. Woolly terminal buds are common on Veronica 

 Chamcedrys, the excess of hair being due to an insect. Mr. Mer, who had 

 studied the subject, came to the conclusion that such hairs, as well as 

 those especially on ribs and veins in a normal state, are due to a localised 



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