26o 



NA rURE 



[January i6, 1908 



In conclusion, Dr. Mascart points out tliat perhaps the 

 most valuable result of the recent attack is the experience 

 gained, and he emphasises the details in the programme 

 which need greater attention, such as the closer observ- 

 ance of the precise prearranged hour, the correct orienta- 

 tion of the final drawing, the care which should be 

 exercised in confirming the presence of a faint marking 

 before showing it on the drawing, and so on. Finally, he 

 ■gives, with full detail, descriptions of various objectives 

 and eye-pieces, showing in each case, by means of 

 diagrams, their action on rays of light. 



Taken as a whole, this preliminary campaign appears 

 to tiave provided very valuable results, and it is to be 

 hoped that future similar organisations will be guided by 

 the experience now gained. 



W. E. R. 



THE A'EIF SCHOOL OF BOTANY, TRINITY 

 COLLEGE, DUBLIN. 



' I ' H I-- siiince schools committee of Trinity College, 

 Dublin, is to be congratulated on the completion of 

 the second item in its scheme for the scientific develop- 

 ment of Trinity College. This project, which was in the 

 first instance originated by Prof. John Joly, F.R.S., and 

 has since owed much to his activity and devotion, was 

 inaugurated in 1901 by a handsome subscription from the 

 chancellor, the Ear! of Rosse. .\t an early stage In the 

 mcAe^iient mutism was .is-.ured bv a muniliccnt gift trcmi 



Viscount Ivcagh. .According to the terms of this gift, 

 Lord Ivcagh undertook to build those departments for which 

 the friends of Trinity College subscribed a capital sum 

 requisite to yield the annual upkeep. Last year the 

 School of Physics was completed, and at the beginning of 

 the present session the School of Botany, the second 

 department which has been benefited by this movement, 

 was opened for work. 



The School of Botany is a two-storied building of cut 

 granite, situated in the east end of the college park, and 

 lies east and west. This orientation gives a large number 

 of windows facing north, with the best light for micro- 

 scopic work. The western end, being octagonal, is occupied 

 by a lecture theatre in the upper storey, on the ground 

 floor by a very fine laboratory for general physiology. 

 The northern side of the upper storev is occupied by a 

 large microscope rooin, which can accommodate about 

 sixty students working simultaneously. Through a large 

 double door in the west end of this room access is ob- 

 tained to the theatre. The auditoriuin in the latter is 

 octagonal, so that every seat is close to the lecture table. 



On the ground floor on the north side is a room for 

 microscopic research, a library, professor's laboratory, and 

 the laboratory for general physiology, which also forms the 

 west end of the building. A solidly built greenhouse run- 

 ning out on the north side of the building is immediately 

 connected with the physiological laboratory ; on the south 

 side of the latter opens a chemical laboratory. In addition 

 the usual fittings in the physiological laboratory, there 



NO. 1994, ■^'OL. 77] 



is a large dark chamber, constructed like a fume cupboard, 

 in which plants may be grown m coinplcte darkness, or 

 illuminated by light transmitted through special filters. 

 The greenhouse has a separate neating system from the 

 rest of the building, and a centrally placed case in it mav 

 be heated by a special radiator to a higher temperature 

 than the rest of the greenhouse. Much thought has been 

 given to the working out of the plan and fittings of this 

 new school, and as it stands the School of Botany in Trinity 

 College inust rank with the best in the British Isles. The 

 architect was Mr. W'm. C. Marshall, of London, who also 

 designed the Botanical Laboratory in Cambridge. 



O.'V THE COLOURING MATTERS OF 

 ELOUERS. 



'X'HIRTV or forty years ago I devoted much attention 

 to the colouring matters in plants, studying them 

 with my newly invented spectrum microscope. I published 

 a few papers on particular branches of the subject, but 

 there are other very wide questions the importance of 

 which I did not perceive until altered circumstances led 

 me to devote my attention to work out at sea. Amongst 

 other things studied was the variation in the colour of 

 flowers, which Is inanifestly a very extensive subject, and 

 for which 1 had only limited opportunity to obtain the 

 requisite material, having to rely to a great extent on wild 

 plants and flowers in my garden. Though the results are 

 incomplete, they are probably characteristic ; and it may 

 be well to publish them, since it is 

 now impossible for nie to complete 

 them, and what I did will at all events 

 serve to show what might be done. 

 The ■ whole subject is very complex in 

 more ways than one. 



The colouring matters of plants may 

 be divided into two di\'isions, viz. 



mh those soluble In water but insoluble in 



■T carbon bisulphide or benzol, and those 



^^^^K soluble in the latter reagents but not 



^^^^^ In water. Both are soluble In hydrous 



' — ^ alcohol of the usual strength. Nearly 



all the blues and purples belong to the 



former, and most of the yellow and 



orange to the latter. 



I found the best way of dealing with 

 the flowers was to boil the petals or 

 other portions in the usual hydrous 

 alcohol, which dissolves both groups of 

 pigments, and, after evaporating to 

 dryness, to re-dissolve the constituents 

 soluble in water, filter, and finally evaporate to dryness 

 in a small saucer, in which, if kept fairly dry, thp pig- 

 ment will remain unchanged for a considerable time. 

 Some pigments may be kept unchanged for a long time 

 in a concentrated solution of lump sugar. 



When re-dissolved in water many of the colouring 

 matters soon become pale or nearly colourless, but recover 

 their colour when evaporated to dryness. I never saw 

 proof of this in living flowers, but it may occur when 

 they die and fade. If there be any colour insoluble in 

 water, it may be dissolved In carbon bisulphide, but this 

 Is seldoiTi the case in blue, red, or purple flowers. 



In those cases where the predominant colour is in- 

 soluble in water, it may be separated by agitating the 

 alcoholic solution with carbon bisulphide, adding a little 

 water. The bisulphide carries down the pigment in solu- 

 tion, which may then be evaporated to dryness in a small 

 saucer and kept. \A'hen dissolved In alcohol or carbon 

 bisulphide the colour fades inore or less quickly, especially 

 in the light, but if sealed up almost absolutely free from 

 air. It will remain unchanged for many years, at all events 

 in the dark. 



Having, then, obtained the pigment in a fit state, the 

 next thing is to examine it when in appropriate solution, 

 either in its natural state or after the additibn of a suit- 

 able reagent. To enter into full detail would make this 

 paper far too long, but it seems desirable to give some 

 particulars in order to show how the various pigments 

 can be distinguished. Speaking generally, this is by their 



