ZOOLOGY AND BOTANY, MIOKOSCOPY, ETC. 607 



The maceration process of Schultze is a valuable aid to operations 

 in microchemistry ; the substance is treated with nitric acid and 

 potassium chlorate either in the cold, or in cases of obstinate samples, 

 is boiled for a short time, when the cells are isolated by the solution 

 of the intermediate lamellae. Amongst the instances given of its 

 utility in food analysis is the separation of those peculiar cells of 

 radiating branchial form which exist in the tea-leaf, and are not found 

 in other leaves used for its adulteration (they are, however, found in 

 some of the Camellia family). 



This treatment has also the advantage of dissolving the coloured 

 incrustations of cinnamon, roasted coffee, &c., and leaving the sub- 

 stances ready for further examination. Potash plays an important 

 part in microchemistry, as it renders many objects transparent which 

 are not made so by other reagents ; it was by successive treatment 

 with potash solution, acetic acid, and iodine that Bohm was able to 

 perceive in chlorophyll the small particles of starch which had hitherto 

 escaped observation. The most striking success in the science is that 

 of Sachs with Trommer's sugar-test, which, with slight modifications, 

 enables the microscopist to identify, and even estimate quantitatively,- 

 cane- and grape-sugar, dextrin, gums, and albuminous substances in 

 single cells. 



The author alludes to the tinctorial methods which are employed 

 in the examination of microbes, but which do not come under the 

 strict domain of chemistry; he urges more extensive use of the 

 Microscope, together with the micropolariscope and spectroscope, and 

 the study of botany and physics among chemists. 



Di'. T. Schuchardt, of Gorlitz (Silesia), has issued a special list 

 of chemical reagents supplied by him for the use of botanical- 

 physiological Institutes, arranged after Poulsen's ' Botanische Micro- 

 chemie.' 



Microscopical Examination of Dyed Silks.* — In an article by 

 M. Marius Moyret, it is pointed out that if the silk fibre is seen 

 lengthwise, it appears uniformly dyed ; but in transverse sections it 

 is found that the dye forms a concentric ring, the depth of which 

 ordinarily diminishes gradually from the circumference towards the 

 centre. 



The observations made by M. Lembert establish, also, that if we 

 dye silk with a simple colour, such as cochineal, the colour penetrates 

 in time more and more towards the centre of the silk, becoming at 

 the same time deeper and deeper; so that, if we take successive 

 specimens from a lot of yarn during dyeing, they will exhibit under 

 the Microscope rings of colour which become broader and broader, 

 until they reach the centre. 



If a silk dyed a light shade of one colour is plunged into a bath 

 of a second colour, and dyed to saturation, the section will show under 

 the Microscope an outer ring, the colour of which is a result of the 

 two dyes employed, and an inner part having the pure tone of the 

 second dye. Or if we plunge a silk dyed to saturation with one 



* Chem. Keview, xi. (1882) p. 203, fiom ' Teiuturier Pratique.' 



