1 88 1.] BOTANICAL LETTERS. 347 



chemical knowledge about plants, and I am so poor, that I 

 appeal to your chanty as a pauper. My question is — Do 

 you know of any solid substance in the cells of plants which 

 glycerine and water dissolves ? But you will understand my 

 perplexity better if I give you the facts : I mentioned to you 

 that if a plant of Euphorbia peplus is gently dug up and the 

 roots placed for a short time in a weak solution (i to 10,000 

 of water suffices in 24 hours) of carbonate of ammonia the 

 (generally) alternate longitudinal rows of cells in every 

 rootlet, from the root-cap up to the very top of the root (but 

 not as far as I have yet seen in the green stem) become 

 filled with translucent, brownish grains of matter. These 

 rounded grains often cohere and even become confluent. 

 Pure phosphate and nitrate of ammonia produce (though more 

 slowly) the same effect, as does pure carbonate of soda. 



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 protoplasm 

 (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. 



