346 SUMMARY OF CUERENT RESEARCHES RELATING TO 



chloride (1 : 500). 4. Wash in water, 5. Then for some minutes 

 in acidulated alcohol. 6. Cedar oil. 7. Canada balsam. 



The advantages of this method are said to be more rapid and 

 more perfect decolorization ; greater resistance of the bacillar stain to 

 the action of alcohol, ether, chloroform, and turpentine oil ; and 

 greater distinctness of the tissue structure. 



Method for Determining the Acids in Plants when combined 

 with Bases. * — Dr. H. de Vries proposes a modification of the 

 alcohol method for determining the amount of free and combined 

 organic acids in plants. The sap is, when necessary, first freed from 

 albuminoids by heating in a closed flask and filtering. In one por- 

 tion the acidity is then tested in the ordinary way by curcuma-paper. 

 To the other portion 10 to 20 times the volume of alcohol of 90 per 

 cent, is added, treated with 1/10 normal potash-ley, and with phenol- 

 phthalein. The deduction of one of the numbers so obtained from 

 the other gives the portion of acids combined with organic bases and 

 with ammonia. 



By this means it can be determined that in rapidly growing 

 organs there is a much larger quantity of organic acids combined 

 with organic bases than free, while in mature organs the latter portion 

 may be as large as the former. Thus, in the sap of mature apices of 

 the stem of Impatiens Boylii there was 1 * 1 per cent, of free acid, 2 • 6 

 per cent, combined with bases; in mature leaf -stalks of Bheum 

 officinale, 8 • 2 per cent, of free acid, 9 • 7 per cent, combined with bases. 



Separation of Chlorophyll.f — Herr A. Tschirch proposes a method 

 for sej)arating chlorophyll from the other ingredients of plants which 

 are soluble in alcohol, ether, carbon bisulphide, &c. I'he alcoholic 

 extract is treated, at the temperature of the water-bath, with baryta- 

 hydrate, by which a deep green barium cyanophyllate is obtained, 

 insoluble in alcohol. The xanthophyll can be separated by saponifi- 

 cation. The barium precipitate is also insoluble in water. If dried 

 with an excess of baryta, or at a temperature of 100 degrees, it is 

 also insoluble in ether and benzin. Dried at a lower temperature, it 

 forms black plates soluble in ether. 



Preparing Starch-grains in Potato. J — Prof. T. J. Burrill gives 

 the following directions : — Starch-grains in the cells of potato can be 

 beautifully shown by first partially drying the part from which 

 sections are to be made, thereby aiding materially the process of 

 cutting. Eemove from a fresh tuber a prism 1/4 in. to 1/2 in. in 

 diameter, and 1 in. or more in length. Expose for a few minutes to 

 moderate heat (hot air from a register is excellent) until the surfaces 

 are quite free from moisture, then allow to remain in the ordinary air 

 of the laboratory for twenty-four hours. The consistence will now 

 be excellent for cutting, and clean cells without ragged remains of 

 ruptured ones may be seen beautifully filled with starch-like baskets 

 of fruit. Mount in water. Stain, if desired, with iodine. 



* Maaiidbi. voor Natuiu-\vet.,1884, No, 9. See Bot. Centralbl., xxiv. (1885) p. 249. 

 t Versamrnl. Dcutscli. Natuif. Strassbiu-g, 1885. See Bot. Ceutralbl., xxiv. 

 (1885) p. 314. J Bot. Gazette, x. (1885) pp. 424-5. 



