Mr. B. Broughton's Experiments on Living Cinchona. 379 



amined the nebulae since ; but probably Mr. Huggins will be able 

 to give confirmatory evidence. 



On the night of February 1st we had a pretty brilliant auroral 

 display. Being at work at the time, I missed part of it ; but as soon 

 as I became aware of its existence I applied the spectroscope. At 

 moments four lines already known were easily visible, the chief line 

 being remarkably brilliant. A much narrower slit than that used 

 could have been borne at the time of maximum display, which, how- 

 ever, lasted only a few moments. I was intent on measuring the 

 lines, as at the time I had no published definite information with 

 reference to other than Angstrom's special line ; but at moments 

 light was seen at the red end of the spectrum sufficiently bright to 

 leave a distinct impression of colour ; when, however, special atten- 

 tion was devoted to that part of the spectrum the aurora had greatly 

 diminished in brilliancy, so that I was unable to make out whether 

 a red line existed, or whether there was a general spectrum at the 

 red end. I incline to the latter opinion, and put it down to the rose- 

 coloured arc ; this arc, however, which seemed pretty brilliant after 

 the streamers had disappeared, did not then give a visible spectrum. 

 Probably this phenomenon has been observed before to better pur- 

 pose ; but I cannot find mention thereof in published accounts. 



Yours truly, 



A. Le Sueur. 



" Chemical and Physiological Experiments on Living Cinchonae." 

 By J. Broughton, B.Sc, F.C.S., Chemist to the Cinchona Planta- 

 tions of the Madras Government. 



The memoir describes the principal scientific results which have 

 been obtained during the last three years, in the course of chemical 

 work on the Neilgherry Cinchona Plantations. 



The chemical characteristics of the various parts of the Cinchona 

 plant are described. The condition in which the alkaloids are met 

 with in the living bark is shown to be that of a slightly soluble tan- 

 nate existing in the parenchymatous cells. 



The order of formation of the alkaloids is shown to be, 1st, un- 

 crystallizable quinine ; 2nd, crystallizable quinine ; 3rd, cinchoni- 

 dine and cinchonine. Reasons are adduced for thinking that the 

 alkaloids are really formed in the tissues in which they are found. 



The effect of the solar rays falling on the bark, either while living 

 on the tree or when separated, is shown to be prejudicial to its con- 

 tained alkaloids. The effect of shielding the bark artificially, and 

 the influence of elevation of the site of growth, are detailed. 



The question as to whether the alkaloids are substitutes for the 

 mineral bases is discussed, and a series of experiments is described, 

 which combine to show either that such substitution does not take 

 place, or does so only in a very partial degree. 



2C2 



