1878.] MISCELLANEOUS BOTANICAL LETTERS. 519 



Now, if slices of root under a cover-glass are irrigated 

 with glycerine and water, every one of the innumerable grains 

 in the cells disappear after some hours. What am I to think 

 of this ? . . . . 



Forgive me for bothering you to such an extent ; but I 

 must mention that if the roots are dipped in boiling water 

 there is no deposition of matter, and carbonate of ammonia 

 afterwards produces no effect. I should state that I now find 

 that the granular matter is formed in the cells immediately 

 beneath the thin epidermis, and a few other cells near the 

 vascular tissue. If the granules consisted of living proto- 

 plasm (but I can see no traces of movement in them), then I 

 should infer that the glycerine killed them and aggregation 

 ceased with the diffusion of invisibly minute particles, for I 

 have seen an analogous phenomenon in Drosera. 



If you can aid me, pray do so, and anyhow forgive me. 



Yours very sincerely, 



Ch. Darwin. 



Mr. Torbitt's Experiments on the Potato-Disease. 



[Mr. James Torbitt, of Belfast, has been engaged for the 

 last twelve years in the difficult undertaking, in which he 

 has been to a large extent successful, of raising fungus-proof 

 varieties of the potato. My father felt great interest in Mr. 

 Torbitt's work, and corresponded with him from 1876 on- 

 wards. The following letter, giving a clear account of Mr. 

 Torbitt's method and of my father's opinion of the proba- 

 bility of its success, was written with the idea that Govern- 

 ment aid for the work might possibly be obtainable :] 



C. Darwin to T. H. Farrer. 



Down, March 2, 1S7S. 

 My dear Farrer, — Mr. Torbitt's plan of overcoming the 

 potato-disease seems to me by far the best which has ever 

 been suggested. It consists, as you know from his printed 



