417 



In sending the paper Dr. M'Cosh writes as follows : — 

 " For the last six weeks or two months I have been prosecuting my 

 inquiries; and the result is a fii'm conviction that there is a truth dis- 

 covered by me, though I am not sure that I have arrived at the cor- 

 rect expression of it. In July I talked with considerable hesitation of 

 the angular measurements submitted by me. Some of them were not 

 made upon a sufficiently large induction. I can now state, with great 

 confidence, that there is a most wonderful correspondence of the 

 angle of the venation of the leaf with the angle of ramification of the 

 stems. I can now measure the angle of the tree with great ease. In 

 my first attempts I tried fully-grown trees ; but the result was far 

 from being satisfactory, as the angle is modified by the weight of the 

 branches. Then I tried the young tree, — the tree pretty fully grown, 

 but whose branches had not been bent. This was my method in July. 

 My common plan now is to take a freely -growing hranch from a 

 healthy tree, and measure the angle of the hranchlets. The careful 

 measurement of a few such branches will give the normal angle of 

 ramification ; and it will be found to be much the same as the angle 

 of venation. I have now a large body of facts on that subject in my 

 note-book, but I am not to trouble you with them at present. I have 

 occasionally met with diflSculties, but no contradictions. As an illus- 

 tration of my difficulties, I may mention that in old, decaying trees 

 the angle even of the lateral branches is wider than the normal angles. 

 I have also an idea that all spines are at a wide angle, and that 

 branches tending to become spines are at a wider angle than the nor- 

 mal one. But instead of forwarding my own observations, I enclose 

 a set of observations, made with instruments, by Mr. Mitchell, upon 

 herbaceous plants. Mr. Mitchell is a schoolmaster at Edzell, about 

 six miles from this. He is possessed of extensive scientific know- 

 ledge, and is a respectable botanist. His own researches in crystal- 

 lography led him to set high value on angles ; and he took up my 

 theory heartily, and has been pursuing the investigation in his own 

 way. He has handed me the results. I take the liberty of forward- 

 ing them to you. I confess I am anxious to keep the matter before 

 the public ; and I should like Mr. Mitchell's researches to be made 

 known. He is quite willing that they should be so, and gives his 

 name openly, and with great confidence that his statements will bear 

 investigation." 



3. Tables illustrative of the Morphology of Plants ; by the Rev. Dr. 

 M'Cosh, Brechin. 



VOL. IV. 3 H 



