ZOOLOGY A.ND BOTANY, MICROSCOPY, ETC. 833 



largest observed measured 0*025 mm. in length and 0*016 mm. in 

 breadth; the most common length was about 0*02 mm. 



Microscopical Investigation of Dyed Cotton Fabrics.* — E. Meyer 

 finds that cotton goods which have been dyed by means of the 

 albumin process can easily be distinguished from articles which have 

 been printed with soluble dyes, by means of the Microscope. For 

 example, if a piece of cotton is first treated with a solution of lead 

 acetate, and afterwards with a chromate, the fibres are uniformly 

 coloured. But if the goods have been printed with a mixture of pre- 

 cipitated lead chromate and albumin, and the colour fixed by steaming, 

 the fibres themselves appear colourless under the Microscope, but 

 patches of coloured albumen are attached to the fibre. 



Microscopical Examination of Water for Organic Impurities.t 

 — J. Brautlecht produces a precipitate in the water by adding to 

 100 cc. 5 drops of a solution consisting of 1 part aluminium 

 sulphate, 1 part hydrochloric acid, and 8 parts water, followed 

 up by one to three drops of liquid ammonia. The precipitate settles 

 readily, and after decanting oif the clear solution, is collected upon a 

 smooth filter, stroked off with a glass rod, and thus transferred to a 

 test-tnbe, in which it is dissolved in ten to fifteen drops of dilute acetic 

 acid. The clear solution is examined with the Microscope, at first 

 alone, and then after the addition of a solution of safiranine. By 

 adding one-half per cent, of gelatine permanent preparations may be 

 obtained on Koch's principle. 



A. Certes t summarizes in a very convenient form the procedure 

 necessary for an effective microscopical examination of water. The 

 more general observations of the first sixteen pages are followed by 

 eleven of practical instructions, in which are dealt with the collection 

 of the water, the employment of reagents and their formulae, preserva- 

 tive liquids, colouring matters, &c. 



For the ordinary examination of microbia the power ought not to 

 be less than 250 or 300. For more extended study, powers of 700 

 to 800 are necessary. 



" The use of staining reagents ought never to be neglected after 

 direct examination, as they define much more distinctly the colours 

 and certain details of structure, such as the vibratile cilia, flagella, 

 nuclei, and nucleoli of the ciliate or flagellate infusoria. Especially 

 important is the part which staining reagents will certainly play in 

 the future in regard to the difierent elements of the protoplasm.§ 



• Journ. Chem. Soc— Abstr., xliv. (1883) p. 751. Ber. Deutsch, Chem. 

 Gesell., xvi. pp. 4r)5-7. 



t Kep. Anal. Chemie und Chem. Zeitung. Cf. Chemical News, xlviii. (1883) 

 p. 180. 



X Certes, A., ' Analyse micrographique des Eaux,' 8vo, Paris, 1883, 28 pp. and 

 2 pla. 



§ Tlie various colouring RuKstaTipes give very different reactions, according to 

 the organisms with which thoy are brought in contact. Manufactured fur the 

 most part for commercial purposes, they are for from being homogeneous. Still 

 more rarely are ti.ey chemically pure. Hence arise mistakes and uncertainty in 

 their use. 



