278 PREPARATION OF REAGENTS \_CH.IX 



served in glycerin jelly prepared as follows : Best clear gelatin, 200 grains. 

 Kaiserling's No. 4 solution, 3000 cc. (Potassium acetate, 100 grams ; glycerin, 

 200 cc.; water, 1000 cc.) Put the gelatin in the potassium-acetate-glycerin- 

 water, mixture in an agate pail and heat over a gas or other stove. Stir. When 

 the temperature is about 55 centigrade add the whites of three eggs well 

 beaten, and stir them in vigorously. Make markedly acid by acetic acid. 

 Continue the heating until the mixture just boils, and then filter through filter 

 paper into fruit jars. It is best to put over the filter paper two thicknesses of 

 gauze (g 330). A piece of thymol in the top of each jar will prevent the 

 growth of fungi, or one can add 5% chloral hydrate. Specimens are mounted 

 in this jelly directly from the No. 4 Kaiserlings, or alcoholic specimens can 

 be soaked in water an hour or more and then kept in some of the melted jelly 

 until well soaked, then mount permanently in the glycerin jelly. At the time 

 of mounting the gelatin is liquified over a water bath, and for every 20 cc. of 

 the gelatin used one drop of strong formalin is added. This is to prevent the 

 liquifaction of the gelatin after the specimen is mounted. Let the gelatin 

 cool gradually after the specimen is in place, then add some melted gelatin to 

 make the vessel over full and slide a glass cover on it. This excludes all air. 

 The cover may then be sealed with the clear gelatin or glue used for gluing 

 wood, or the cement used in mending crockery. Finally one can seal with 

 rubber cement if desired. (See W. H. Walters, N. Y. Med. Record, Dec. 

 22, 1906.) 



\ 410. Chloral Hematoxylin. Potash alum 4 grams. Distilled water 

 125 cc.; Hematoxylin crystals ^ gram. Boil 5 to 10 minutes in an agate dish. 

 After cooling, add 3 grams of chloral hydrate and put into a bottle. This will 

 stain more rapidly after a week or two if the bottle is left uncorked. It takes 

 from I to 5 minutes to stain sections. Sometimes a longtime. Use after any 

 method of fixation. 



It may be prepared for work at once by the addition of a small amount of 

 hydrogen dioxid (H,O 2 ). 



If the stain is too concentrated it may be diluted with freshly distilled 

 water or with a mixture of water, alum and chloral. If the stain is not suffi- 

 ciently concentrared, more hematoxylin may be added. Proc. Amer. Micr. 

 Soc., 1892, pp. 125-127). 



$ 411. Hematein. This is used instead of hematoxylin, as it is believed 

 to give more satisfactory results. Prepare as follows : Put a 5% solution of pot- 

 ash alum in distilled water and boil or leave in a steam steralizer an hour or two. 

 While warm add i per cent of hematein dissolved in a small quantity ot 

 alcohol. After the fluid has cooled add 2 grams of chloral for each 100 cc. of 

 solution. (Freeborn, Jour. Ap. Micr., 1900, p. 1056.) 



$412.- lodin Stain for Glycogen. lodin i}4 gram ; iodid of potassium 3 

 grams; sodium chlorid \ l / 2 grams; water 300 cc. For very soluble glycogen 

 one can use 50% alcohol 300 cc. instead of water. The iodin stain is the 

 most precise and differential for glycogen. For sectioning tissues or embryos 

 are fixed and hardened in 95% or absolute alcohol. Sectioned by the paraffin 

 method, or by the collodion method, but for permanent preparations the 



