WITH THE MICROSCOPE. 295 



tures thus preserved in syrup to the precise extent required for 

 further minute dissection, and even very hard textures may thus be 

 softened, so that by gradually increased pressure and careful manipu- 

 lation, exceedingly thin layers can be obtained without the relation 

 of the anatomical elements to each other being much altered, and 

 without any of the tissues being destroyed. 



367. The Carmine Fluid for Staining Germinal Matter. The 

 composition of this fluid has been already given in p. 109, where also 

 will be found the directions for making it. This fluid will be re- 

 quired to be made stronger or weaker in particular cases and great 

 advantage sometimes results from diluting it with alcohol. The 

 quantity to be added to obtain the best results can be ascertained by 

 trying a few experiments. 



The length of time required for staining the tissue successfully 

 varies much. Some tissues are coloured very slowly. Fibrous tissue, 

 bone and cartilage, even in very thin sections, will require twelve 

 hours or even more, but perfectly fresh soft embryonic tissues, and 

 very thin sections of the liver and kidney, thin sections of morbid 

 growths rich in cells, may be coloured in half an hour, while the 

 individual cells of the above structures, placed on a glass slide, 

 may be coloured in less than a minute. I have often coloured the 

 germinal matter of the fresh liver cell in a few seconds, by simply 

 allowing the carmine fluid to flow once over the specimen. 



368. Glycerine and Syrup. 



1. Weak common glycerine of about the specific gravity 1050. 



2. The strongest Prices glycerine that can be obtained. 



3. Syrup made by dissolving, by the application of a gentle heat 

 in a water bath, 3 Ibs. of sugar in a pint of distilled water. A weaker 

 solution can be prepared, as required, by mixing equal parts of syrup 

 and water. 



Although I have found syrup of great value in many special 

 enquiries, I cannot recommend it for general use, in consequence of 

 its liability to be invaded by numerous fungi, which often destroy the 

 specimen. 



369. The injecting Fluid. For injecting the finest capillaries in 

 specimens which are to be mounted for the highest powers, I have 

 found a slight modification of the original Prussian blue fluid, the 

 composition of which is given in p. 93, fulfil all the requirements. The 

 following mixture has succeeded admirably in my hands, and I there- 

 fore recommend it strongly. It p enetrates to the finest vessels, and 

 may even be ^forced into developing capillaries which are only in 

 part pervious. It never forms a deposit. The specimens injected 



