2724 Journal of Applied Microscopy 



that while the cancellous portions of the bone are still firm, being supported by 

 the paraffin, the dense bone which surrounds the labyrinth will have become 

 quite pulpy ; indeed, the labyrinth should lie almost loose in the pulp ; if this is 

 not so, the preparation should be put back into the acid and left longer, and the 

 solution should be made stronger by adding a little more hydrochloric acid. 

 After decalcification the mass should be thoroughly washed for twenty-four hours 

 in gently running water, care being taken that it does not get roughly handled 

 during the process. Some of the cancellous portions of the bone may now be 

 picked very carefully away with the sharp point of a knife, and then the mass is 

 carefully removed to absolute alcohol, where it remains for about ten days, tbe 

 alcohol being changed several times. From the alcohol it is transferred rapidly 

 to xylol, which slowly dissolves out the paraffin and leaves the membranous 

 labyrinth transparent. Surrounding portions of cancellous tissue maybe slightly 

 adherent, but they can be separated by fine sharp scissors as the structure lies 

 in the xylol. If the dehydration has been thorough, extremely delicate structures 

 do not collapse or shrink when the paraffin is removed. The specimen is pre- 

 served in xylol in the glass jar when the paraffin has been melted out. The 

 courses of the various portions of the nerves stand out very plainly, and may be 

 shown still more clearly if the specimen has previously been stained and fixed 

 with osmic acid. Very pretty specimens may also be made by injecting the 

 endolymph spaces (before hardening) with carmine gelatine, the injection being 

 done through the aqueductus vestibuli. The blood vessels may be injected 

 through the internal auditory artery, also of course before hardening. r. p. 



A Simple Apparatus and Method for In the Arch. f. Schi/fs- mid Tropen- 

 Water Analysis. Hygiene (Bd. VII, Heft 9, pp. 4.34-436, 



1903), Dr. Markl describes a simple apparatus which he has used with much 

 success in making chemical analyses of water. While his use of it has been for 

 hygienic purposes, it seems evident from the account given that the apparatus 

 will prove very useful for biologists who wish, in the course of ecological or 

 experimental work, to make chemical analyses of water. The apparatus is made 

 by the firm of Burroughs Wellcome & Co., in London. It consists of several 

 glass cylinders, with graduations to TO ccm., a shaking flask with ground glass 

 stopper, a flask for boiling the water, an alcohol lamp with tripod foot, a nickel 

 dish, several glass rods, and a number of accurately measured reagents in tablet 

 form together with small sealed glass spheres containing Nessler's reagent. The 

 tests are made in the following way : After the color, degree of turbidity and 

 odor of the water have been determined a sample is boiled away in the nickel 

 pan in order to estimate the content of dry substance. The hardness of the 

 water is determined by adding to 70 ccm. of the water soap tablets till the foam 

 formed by vigorous shaking persists. Each tablet indicates four degrees of 

 hardness on the scale used. The chlorine is titrated out in a glass cylinder with 

 silver nitrate pastilles, with the addition of a potassium bichromate tablet as an 

 indicator. Each pastille indicates 2 mg. of chlorine. The organic matter is 

 determined by means of tablets of potassium permanganate in hot solution. 

 Each tablet indicates 1/10 mg. of absorbed oxygen. The presence of ammonia 



