Of MICROSCOPIC OBJECTS. 193 



For the injecting fluid, take 24 ounces of the coloured 

 liquid thus prepared, and three ounces of good gelatine. 

 A-llow these to remain together twelve hours, and then 

 dissolve by the heat of a water-bath ; after which it should 

 be strained through fine muslin. 



As this injecting fluid contains gelatine, the hot water, 

 and other contrivances mentioned in a former part of the 

 chapter, will be necessary here also, but no peculiar treat- 

 ment will be required. 



Since writing the above concerning carmine injection, I 

 have had the misfortune to lose my friend Mr. Dale, but not 

 before we made scores of experiments together, with this 

 formula. Our experience, I may say without vanity, justi- 

 fies me in declaring that a good operator can get results 

 equal to any that he will receive from the Continent, as far as 

 colour and distinctness are concerned. The colour, being 

 thoroughly precipitated, cannot stain the tissues, and the 

 course is thus clear and well defined. If the object is small, 

 it is well to use the mixture with 25 or 30 ounces of water 

 instead of 40 ; but, with this exception, I know of nothing 

 that needs alteration. I have, time after time, measured 

 vessels thoroughly filled with good colour especially 

 amongst fatty portions, and found them betwixt l-3000th 

 and l-4000th of an inch. As some young students might 

 say " Give me an account of something done with it," I will 

 endeavour to describe my use of part of a horse's leg. My 

 friend Mr. Hepworth wrote to me that he had a horse's leg, 

 and should be glad if I would come over with sufficient car- 

 mine to inject it. I took three pints of solution, and may 

 here mention that, with a very slight loss indeed, all this 

 liquid was thrown into our subject. The leg was cut off 

 just beneath the knee, and before using it we allowed it to 

 remain in water about 80 or 90 Fahrenheit two or three 

 hours, and then introduced our syringe into an artery at 

 the top. As I have no faith in any mechanical contrivance, 



o 



