1092 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Double Staining Vegetable Sections.* — It is found that on lifting 

 thin vegetable sections from one fluid to another, so many times as it 

 it is necessary to do in double staining them, they are liable to get 

 broken, and Mr. F. Beddow suggests the following method as a 

 means of avoiding the difficulty : — ■ 



After the sections have been cut and the paraffin removed from 

 them, they should be put in specimen tubes (1 in. long and 7/8 in. 

 wide i, and a piece of muslin tied over the mouth of each tube. To 

 bleach the sections the tubes are put in chlorinated soda, or in a 

 bottle containing water, through which chlorine is passed. After 

 bleaching, the tubes (still keeping the muslin over the mouths) should 

 be put in a large basin of water, and the water changed several times, 

 then the different stains can be poured into the tubes and poured out 

 a^ain. The sections can be bleached, washed, put in a mordant, 

 stained with carmine, put in an acidulated water to fix the carmine, 

 stained with anilin green, and cleared in benzol or oil of cloves, 

 without once handling them. 



Congo Red as a reagent for free acid.f — According to Dr. H. 

 Scholz, Congo red, a dye easily soluble in water, appears to have no 

 action, even in strong solutions, on the lower organisms. It may 

 therefore be employed to demonstrate free acids which occur as the 

 result of the tissue changes of living microscopical organisms. If 

 Eotatoria be examined in the coloured solution they are seen at first 

 unstained in the red-yellow field of view ; afterwards, while tho 

 investment, tail, and wheel-organs are unstained, the jaws appear a 

 dark rusty red ; the stomach walls assume a blue colour, as also, 

 transitorily, the part between the oral cavity and stomach and the 

 upper part of the exit gut. In Yorticella and Infusoria reliable results 

 were not obtained. As the blue colour of the acidly reacting parts 

 could not be elicited by transmission of carbonic acid through the 

 solution it was concluded that some other acid was the cause. 



Decoloration of stained Nuclei and Micro-organisms by salt 

 solutions.! — Dr. A. Gottstein finds that in addition to silver nitrate 

 and potassium bichromate, the decolorizing property is possessed by 

 other salts, such as iodide of potassium, chloride of sodium, the 

 carbonates and sulphates of soda and magnesia, alum, &c. The degree 

 of decoloration depends on the concentration of the salts, and the 

 duration of their action. As well as nuclei, typhoid, pneumonia, 

 gonorrhoea, and putrefaction Bacteria are unstained by these salt 

 solutions. The bacilli of tubercle, lepra, and syphilis are less 

 susceptible than the preceding, and are only deprived of their colour 

 by concentrated solutions. Fuchsin is more sensitive to the 

 decolorizing influence than the violet stains. The reason for the 

 decolorizing action is to be sought in the insolubility of the anilins 

 in the solutions of these salts. 



* Sci.-Gossip, 1886, p. 233. f Centralbl. f. d. Med. Wiss., 1886, p. 449. 

 J Fort=chr. d. Med., iii. (1S85) p. 627. 



