ZOOLOGY AND BOTANY. MICROSCOPY, ETC. 601 



is 65 per cent., are well-suited for the purpose. The pollen-grains of 

 Tradescantia virginica will produce tubes 100 /a long in two hours. 



Continuity of Protoplasm in Plants.* — Mr. J. M. Coulter finds the 

 cortex of the " buck-eye " (^Msculus Pavia) to bo a favourable object for 

 demonstrating the continuity of proto{)lasm. The strands which connect 

 the protoplasts are here so large that they may be satisfactorily seen 

 with a magnification of 250, and very well studied with one of 500 dia- 

 meters, and in neither case is there any necessity for using an immersion 

 objective. Mr. Coulter carefully slices the periderm from a twig about 

 1/4 to 1/2 in. in diameter, so as to expose the cortex ; then makes a thin 

 tangential section from the latter, and immerses in a solution of iodine 

 in potassium iodide until it turns brown, washes to remove the excess of 

 iodine, and mounts in water; at the edge of the cover-glass is then 

 placed a drop of pure and two drops of 75 per cent, sulphuric acid; 

 after this has been drawn under, the section is very thoroughly washed, 

 and the water replaced by glycerin. Even a low power will now show 

 the very much swollen and transj)arent walls crossed in every direction 

 by protoplasmic strands connecting the contracted brown protoplasts. 

 To make a permanent mount, it will be necessary to use some stain for 

 the protojjlasts and their connecting strands ; otherwise the strands 

 gradually become so transparent in the glycerin as to be almost invisible. 



C4) Staining and Injecting-. 



Staining^ reagents for Wood-f — Dr. E. Nickel adduces reasons for 

 the^view that the so-called lignin-reaction of woody tissue is not due to 

 the presence of a definite chemical compound, but to the aldehyde-con- 

 stituents of the wood. 



Staining of sections to show Micro-organisms in situ.J — Dr. H. 

 Kuhne opines that it is a mistake to use strong solutions of dyes to 

 show the presence and position of micro-organisms in sections of animal 

 tissue, as the differentiation is very difficult to bring off, owing to the 

 compulsory use of decolorizing agents. He advises the employment of 

 weak solutions, so that the tissues are not overstained, and to differ- 

 entiate with acid or basic auilins. 



The author states that he has given up the use of alcohol as a dehy- 

 drating agent, and uses only auilin oil for this purpose. In demon- 

 strating the jiresence of bacteria in tissues, he first used anilins, basic 

 and acid, dissolved in oil of cloves. This last reagent he has now dis- 

 carded altogether in favour of anilin oil, which medium he now employs 

 universally, i. e. stained or unstained, accoi ding as it is desired to use 

 it as an extracting agent, a dehydraut, or for the pur^jose of double 

 staining. 



New and rapid method of staining the capsule of Bacillus pneu- 

 monisB. § — Dr. U. Gabbi employs the following method for staining the 

 capsule of Bacillus Pneumoniae Fraeukel. The sputum to be examined 

 is spread on a cover-glass and quickly dried in a spirit-lamp flame. 

 Two or three drops of a solution of 2 • 5 gr. carbolic acid, 1 gr. fuchsin, 

 and 15 gr. alcohol in 100 gr. distilled water, are then dropped on the 



* Bot. Gazette, xiv. (1889) pp. 82-3 (1 fig.), 

 t Bot. Ceutralbl., xxxviii, (1889) pp. 753-6. 

 i Annalos do Micrographie, 11. (1889) pp. 358-01. 

 § La Riforma Medica, 1889, No. 31. 



