306 



SCIENCE. 



gum water, or Brunswick black. For very small objects a 

 small circle of the gelatin is turned in the centre of the 

 slide, and then allowed to dry. The objects are arranged 

 on the spot, and then, by carefully breathing on the slide, 

 they are fixed in position. If larger objects are to be fixed 

 to the slide a spot of gelatin or gum that the object will 

 entirely cover is put on, and after drying, the object is fixed 

 in the same way. For larger and heavier objects a circle 

 of Brunswick black is turned, and after it has been thor- 

 oughly hardened by heat, so that when cool a needle point 

 will not mark it easily, the object is arranged on the spot 

 and fastened by warming again. 



In whatever way the object is fastened, the next thing to 

 be done is to lay the slide on the plate and heat it until it 

 is perfectly dried and ready to be covered. 



The slide is then centered on the table and a circle of 

 shellac, which has been thickened and colored with Chinese 

 vermillion, is run around the specimen, at such a distance 

 from it that its inner edge is just larger than the cell to be 

 used. The cell is then laid on, centered, and pressed hard 

 to set it. If the slide is slightly warm and the cement 

 thick, it will not run at all, but will hold the cell firmly in 

 place, so that the cover can be put on at once. If it is thin 

 it must first be allowed to harden somewhat. When ready, 

 as it will be in a few moments if properly managed, a ring 

 of the same cement is run on the cell and the cover is then 

 laid on, pressed down, clipped in position, and the mount 

 laid aside to harden. It is well in an hour or so to remove 

 the clip and run cement in the joints between cover-glass 

 cell and slide, in order to be certain that no air-holes re- 

 main. It can then be reclipped, and set aside until the 

 cement is perfectly hard. The mount is complete and will 

 last a long time if proper care is taken of it. I think for 

 security it is well to put on additional rings of cement 

 more elastic than the shellac, and to make a final finish for 

 the sake of appearance. I, therefore, put on a ring of 

 white zinc cement which completely fills up the joints, and 

 makes a smooth surface from cover-glass to slide. This 

 must harden several days, and the slide is then complete, 

 unless additional rings are run on for a finish. 



In making the rings on slides it is not always easy to 

 make the edges true, and sometimes the cement spreads 

 too far. In such cases I turn them down with the point of 

 a knife until they suit. If the cement is taken just at the 

 right time this is easily done, and it improves the appear- 

 ance very much." 



phyll. Thus, without desiring to affirm it absolutely, Prof. 

 Schnetzler supposes, a priori, that there is in plants only one 

 coloring matter — chlorophyll, which, being modified by cer- 

 tain agents, furnishes all the tints that flowers and leaves 

 exhibit. As for white flowers, it is well known that their 

 cells are filled with a colorless fiuid, opacity being due to 

 air contained in the numerous lacuna? of the petals. On 

 placing the latter under the receiver of an air-pump, they 

 are seen to lose their opacity and to become transparent as 

 the air escapes from them. 



BOTANY, 



The Color of Flowers. — At a recent meeting of the 

 Vaudois Society of Natural Science, Prof. Schnetzler read 

 an interesting paper on the color of flowers. Hitherto it 

 has generally been supposed that the various colors ob- 

 served in plants were due to so many different matters — \ 

 each color being a different chemical combination without 

 relation to the others. Now, however, Prof. Schnetzler 

 shows by experiment that when the color of a flower has 

 been isolated by putting it in alcohol, one may, by adding 

 an acid or an alkali, obtain all the colors which plants ex- 

 hibit. Plants of Pseony, for example, yield, when macer- 

 ated in alcohol, a violel-red liquid. If some acid oxalate 

 of potassa be added, the liquid becomes pure red ; while 

 soda changes it, according to the proportion used, into vio- 

 let, blue or green. In the latter case, the green liquid 

 appears red by transmitted light, just as a solution of chlor- 

 ophyll does. The sepals of P;cony, which are green bor- 

 dered with red, become wholly red when placed in a solu- 

 tion of acid oxalate (binoxalate) of potassa. These changes i 

 of color, which may be obtained at will, may quite well be 

 produced in the plant by the same causes; since, in all 

 plants, there always exist acid or alkaline matters. Fur- 

 ther, it is stated that the transformation from green into red, 

 observed in the leaves of many plants in autumn, is due to 

 the action of the tannin which they contain, on the chloro- i 



Professor W. W. Bailey, of Brown University, states 

 that the herbarium of the late Col. Stephen T. Olney, 

 of Providence, R. I., was left by his will to Brown Univer- 

 sity, on condition that it be placed in a fire-proof building. 

 It is probably known to the readers of "Science" that 

 Col. Olney was an invalid and incapacitated for business 

 during the last years of his life. At that time the herbarium, 

 which had been stored in Butler Exchange, was trans- 

 ferred by the trustees to the fire-proof library building of 

 Brown University, the only edifice possessed by the college 

 which would fulfil the requirements. Professor Bailey 

 was requested to examine and arrange the collections, 

 which he did in connection with Mr. James L. Bennett. 

 He is greatly indebted to this gentleman for valuable 

 suggestions and assistance which his natural neatness 

 of method and mature experience rendered easily pos- 

 sible. He it was who arranged the Carices (which were 

 Col. Olney's specialty), together with the lower Crypto- 

 gams, many of which he had himself collected. 



They found this elegant herbarium, one hardly surpassed 

 by any private collection in America, badly injured by in- 

 sects. The first work, then, was to poison what could be 

 saved. It is not an exaggeration to say that one-third of the 

 Phanerogams had suffered. In places a whole genus would 

 be riddled by the Anthrenus. It was a sad sight ; for the 

 specimens had been prime, were superbly mounted, and 

 many of them impossible to replace. Col. Olney was so 

 neat in his methods that he disliked to see a blemish on 

 any paper ; hence his very sense of order was perhaps a 

 means of loss. Every plant had to be thoroughly poisoned. 

 Now that the college has come into possession, it will be 

 necessary to throw out mutilated specimens and replace 

 them by others. Mr. Bennett and Professor Bailey stand 

 ready to fill the vacancies from their own herbariums. 



The collection is a fine one in every way. In Rhode 

 Island plants it is only equalled by that of Mr. Bennett. 

 It is very rich in Southern and Western plants of Hale, 

 Chapman, Curtis, Ravenel, Fendler, Parry, Thurber and 

 many other well-known collectors. There is a fine set of 

 Wright's Cuban plants, of Robin's Potamogetons, of Sulli- 

 vant's and Austin's Mosses, etc., etc. Indeed the owner 

 spared no expense (and he was a wealthy man) to build up 

 his herbarium. In the genus Carex it must long remain 

 unique and classic. There is much raw material and many 

 duplicates in Carex. As Colonel Olney's correspondence 

 shows him to have been in debt as regards exchanges, Pro- 

 fessor Bailey, who now has charge of the herbarium, would 

 be pleased to communicate with such botanists as have not 

 received returns. He will then, acting under the direction 

 of the college authorities, endeavor to discharge all such 

 obligations. Col. Olney bequeathed a fund of $10,000 for 

 the increase of his herbarium and library. The latter, con- 

 taining 712 volumes also conies to Brown University, to- 

 gether with his Chevalier and Smith & Beck's microscopes 

 and much valuable apparatus and material. With another 

 $25,000 left by the deceased Colonel, a professorship of 

 Natural History has been created. One of the duties of 

 the professor is to give lectures on Botany. 



We .in- under obligations to the Bulletin of the Torrey 

 Botanical Club, for occasional botanical notes. This 

 Journal has now been published for ten years, and was 

 established as a means of communication for botanists. The 

 address of the editor is, W. H. Leggett, 54 East 81st 

 street, New Yoik City. The rates are one dollar per 

 annum, so that its cost will hardly be a bar to its use by 

 botanists. We can probably arrange club rates for our 

 subscribers. 



