XVII. On the Deveidatinf of the Leaves of Cotyledon calycina ; in 
a Letter to A. B. Lambert, Esq., Vice-President of the EIER 
Society. By see Heyne, M.D. F.L.S. 
A Read April 20, 1813. 
Dear SiR, | 
I na» an opportunity some time ago of mentioning to you a 
remarkable deoxidation of the leaves of a plant in day-light. 
As the circumstance is in itself curious, and throws great light on 
the opinion of those celebrated philosophers who have written on 
the subject, I will state it shortly in this letter, which if you . 
please, you may in extract, or in any other way you think pro- 
per, lay before the Society. 
The leaves of the Cotyledon calycina, the plant called by Mr. 
Salisbury Bryophyllum calycinum, which on the whole have an 
herbaceous taste, are in the morning as acid as sorrel, if not 
more so; as the day advances, they lose their acidity, and are 
tasteless about noon; and become almost bitterish towards even- 
ing. ‘This is the case in India, where this plant is pretty gene- 
rally cultivated in our gardens; and it remains to be seen if the 
same takes place in the hot-houses in England, where it has been 
lately introduced. | 
I have seen this plant but once in this country, and that was at 
Mr. Loddiges’, at Hackney, about twelve o'clock in the day-time, 
when I found it quite tasteless. The distance of that place from 
2r2 my 
