252 



NATURE 



[July 29, 1875 



I fed pot A with, pure distilled water, B with strong decoction 

 of beef, and C with -0026 per cent, solution of phosphate of 

 ammonia. 



The results are briefly these, after seventeen days' experimen- 

 tation : In A all the plants are growing and looking perfectly 

 healthy, though those with four leaves buried and the roots 

 exposed, looked sickly for a few days. Now, however, they are 

 putting forth new leaves ; so are those with all the leaves pinched 

 off and the roots buried. 



Those with the roots pinched off and all the leaves buried are 

 burstinc; into flower. 



In B all the plants are greatly damaged, those with the leaves 

 only, and those with the roots only are quite dead. Those with 

 the. roots off and the leaves buried have their leaf stalks much 

 blackened, as described by Mr. Darwin as the result of over- 

 feeding. The pot smells strongly of ammonia. 



In C the condition is very much as in A, but the growth has 

 been much more active, for some of the plants with the roots off 

 and leaves buried have pushed new leaves up through the sand, 

 and those whh only four leaves buried have put out numerous 

 new leaves, and their roots are quite dry. In one of these latter 

 I amputated the roots five days after it had been in the pot, and 

 it is as vigorous as the rest. About '03 of a grain of phosphate 

 of ammonia has been supplied to this pot during twelve days for 

 twelve plants. 



It is, therefore, perfectly certain that the sun-dew can not only 

 absorb nutriment by its leaves, but that it can actually live by 

 their aid alone, and that it thrives better if supplied with nitro- 

 genous material in small quantities. 



The nitrogenous matter is more readily absorbed by ihe leaves 

 than by the roots, for over-feeding kills the plant sooner by the 

 leaves alone than by the roots alone. But it is also certain that 

 the roots absorb nitrogenous matter. 



On June 17 I read a paper to the Birmingham Natural History 

 Society, in which I announced that I had been able to separate 

 a substance closely resembling pepsine from the secretion of 

 the Di'osera didiotoma. Since then I have also separated it from 

 the fluid taken from the pitchers of various nepenthes. 



The secretion from the Dichotonia was gathered on a feather 

 which was washed in pure distilled water. It made the water 

 very viscid, although probably the whole amount gathered from 

 the only available plant was not more than six or eight minims, 

 and an ounce of water was used. One cubic centimetre of this 

 solution to five cubic centimetres of fresh milk separated a thick 

 viscid mass, whh a very small quantity of whey, in about twelve 

 hours, at the ordinary temperature of the atmosphere. This 

 mixture was kept in an open test glass three weeks, but it never 

 became putrid. 



The remainder of the solution was accidulated with dilute 

 phosphoric acid, and then a thin mixture of chalk and water was 

 added drop by drop till effervescence ceased. The mixture was 

 allowed to stand for twenty -four hours and the clear fluid 

 removed. 



The precipitate was treated with very dilute hydrochloric 

 acid, and the result treated with a saturated solution of pure 

 cholestearine made by Beneke's method, in a mixture of abso- 

 lute alcohol and absolute ether. The mass which separated 

 was then dissolved in absolute ether, and in the resulting water 

 was suspended a greyish flocculent matter which, on examina- 

 tion was found to be perfectly amorphous. It was dried at a 

 temperature of 42°, and weighed, roughly, a third of a grain. 

 It was partially soluble in distilled water, not at all in boiling 

 water, greatly soluble in glycerine, and it produced the charac- 

 teristic viscid change on a small quantity of fresh milk. 



Fluid was taken from three nepenthe pitchers which had not 

 opened their valves, to the amount of 2-3 cubic centimetres. It 

 was treated in the same way as described above, and yielded a 

 trace of the flocculent matter. Seven cubic centimetres of fluid 

 from pitchers which had been long open and contained abundant 

 insect debris, yielded the same flocculent substance. It has a 

 specific gravity fractionally greater than water, and has reactions 

 quite similar to the substance separated from the D. dichotonia, 

 and which I propose to call droserine. 



At Mr. Darwin's suggestion I have tried the action of the 

 fluid of four virgin pitchers of the Nepenthe phyllamphora on 

 cubes of albumen one millimetre in measurement. After twenty- 

 eight hours immersion there was no indication of change by any 

 one of the four fluids. Yet the chemical differences in all four 

 were very marked. One only was viscid, yet it contained not a 

 trace of the grey flocculent matter which I regard as the ferment. 



One only was at all acid, the other three being absolutely 

 neutral. One contained quite a large quantity of the ferment, 

 whilst the fourth had no reaction in silver lactate, so that I ima- 

 gine it was only pure water. On the contrary, fluid taken from 

 pitchers into which flies have previously found their way is 

 always very acid, has a large quantity of the ferment, and acts in 

 a few hours on cubes of albumen, making them first yellow, then 

 transparent, and finally completely dissolving them. 



The quantities obtained were too small to submit to analysis, 

 and I am not sufficiently an adept in chemical manipulation to 

 give a better account of this interesting substance. 



When studying the nepenthes, I was puzzled to see the use of 

 the channel which exists on the back of the pitchers, and which 

 is formed by two ridges furnished with spikes in most of the 

 nepenthes, but not in all, which run up to the margin of the lip 

 of the pitcher. 



I found that one plant under observation was infested by a 

 small red ant-like insect, numbers of which had found their way 

 into one particular pitcher, I observed two or three on the 

 leaf of this pitcher, and I carefully observed their movements. 

 They occasionally approached the edge of the leaf, but always 

 turned back when they encountered the spikes which run down 

 the margin, and which are the same as are seen on the ridges. 

 In all the mature pitchers the stalk hangs in contact with the 

 pitcher just between those two ridges, about half way between 

 the attachment of the stalk and the lip of the pitcher. 



At this point of contact the insects marched on to the pitcher, 

 and then, of course, found themselves on the pathway between 

 the ridges. Here they again always turned back when they 

 encountered the spikes, so that they soon found their way to the 

 lip. 



Here they paused, and seemed to enjoy some secretion which 

 seems to be poured out on the glazed surface of the lip. Then 

 they travelled onwards, and met the fate of their companions. 

 I found about thirty of these insects in this pitcher, and as they 

 were in various stages of digestion, I presume they were en- 

 trapped at different times. I could see no reason why they all 

 went to this pitcher, though no doubt there was one. The 

 secretion in which they were being digested was very viscid and 

 very acid. In the unopened pitcher the secretion is only faintly 

 acid and not at all viscid. The secretion is increased, therefore, 

 as Mr. Darwin has shown to be the case in Drosera, in quality 

 after food has been taken in. 



The footpath extending from the petiole to the lip of the 

 pitcher, armed on each side with a chivaux-de-frise, to prevent the 

 prey wandering off, is a contrivance which is manifestly for the 

 advantage of the plant ; so also, is the umbrella which is extended 

 over the orifices of the pitchers in many of the nepenthes. Its 

 obvious use is to prevent dilution of their gastric juice. In some 

 the lid does not cover the orifice ; probably there is something 

 special in their habits. 



The glands which line the pitchers differ considerably from 

 the Dioncca, and they are placed 'in curious little pockets of 

 epithelial cells, the meaning of which is not evident. 



Lawson Tait 



Curious Phenomenon in the Eclipse of 1927 

 On the morning of June 29, 1927, there will be the next solar 

 eclipse in England in which anything in the shape of totality 

 can be seen. In an examination of eclipses I made two or three 

 years ago, I considei-ed this one would be total for a brief period 

 in the north of England, as mentioned in Nature, vol, xii, p. 

 213. But the curious point worthy of notice is the following : — 

 As the moon's disc only just overlaps that of the sun, we may 

 expect to see the red flames visible, not as prominences, but as a 

 line of red light encircling the sun for a few moments. The 

 probable appearance of such a phenomenon in a slightly total 

 eclipse of the sun was pointed out by Prof, Grant in a paper in 

 the December Notices of the R.A.S., 1871 (q.v.) The eclipse 

 of June 29, 1927, seems to afford such an opportunity as the 

 Professor wished to find out. Although this eclipse, therefore, 

 is but an apology for a total one, it may acquire an interest of its 

 own for posterity. See my little work, "Eclipses Past and 

 Future" (Parkers) on this subject. Samuel J. Johnson 



Upton Helions Rectory, Crediton, Devon 



Spectroscopic previiion of Rain with a High Barometer 



My letter of last Monday (in last week's Nature, p, 231) 

 having been sent off when we (in Edinburgh) were still in the 



