PROCEEDINGS OF THE SOCIETY. 
161 
optical puzzle than was the case with the lower powers ; in fact, the 
effect obtained was one which, if it had occurred in any object where 
there were fibres or striae crossing each other in a similar way, would 
easily lead to the true character of such an object being mistaken. 
There was one other little matter which he/thought it might be 
of some interest to mention. Among the species of black fungi which 
were found infesting orange and other trees, and which appeared in 
great abundance last autumn, one attacked a bay tree or true laurel 
growing out of doors, and it seemed able to remain and grow upon 
the leaf for a long time without injuring it. Many of the leaves 
which he had examined did not seem at all damaged, although the 
fungi had remained upon them from last autumn to the present time. 
It was quite easy to take them off with a penknife, and as there was 
no penetration of the fungus into the structure of the leaf, as soon as 
the film was removed the leaf seemed all right again. A fungologist 
to whom he had shown it, thought it to be a species of Capnodium. 
(Drawings of its general appearance were then made upon the black- 
board.) An interesting physiological question arose in connection 
with it : What was the good of the plant to the fungus if it did not 
penetrate the structure of the leaf? The respiration of plants was 
the same in principle as that of animals, but they were also able to 
do what animals could not do, and that was to digest carbonic acid. 
Whether any of the matters exhaled by the leaf were of use to the 
fungus, he could not say. Specimens of the leaves with fungi upon 
them were then handed round, in the hope that some gentleman 
present might be able to identify them. 
Mr. Thomas Palmer said he had found a very similar fungus 
recently upon the leaves of the Arbutus. It did not penetrate the 
leaf, but was merely a kind of surface fungus, and could be readily 
brushed off by tolerably stiff bristles. He had, however, observed 
that when the black mass had been removed, the leaf underneath was 
of a much lighter colour than the surrounding parts. 
The President had found a number of small beads, in irregular 
grape-like groups, in connection with it, which he thought might pos- 
sibly be spores. 
Mr. Vize said that, without examining the specimens more closely, 
he could not determine the species ; his impression, however, was, that 
it was an immature form of Capnodium, which, as a rule, it was very 
difficult to find in England in the mature state. Under a bell glass, 
with sufficient warmth and moisture, they could be got to develop 
more fully. 
The President inquired if Mr. Vize could answer the question, 
of what special use was the plant to the fungus ; what caused it to 
establish itself there ? 
Mr. Vize could only suppose that the spores had dropped at some 
time upon the leaf, and having found a nidus, had there developed. 
It was well known that the spores were carried about in the air, and 
that special spores were developed in special positions which hap|3cned 
to favour their habit of growth. 
Dr. M. C. Cooke, in reply to a question from the President, said 
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