CELESTIN BLUE B-EOSIN-STAINED INTESTINE HI 



500 cc. capacity be obtained and a hook inserted into the center of its stopper, 

 from which the object can be suspended. The majority of wide-mouthed, glass- 

 stoppered jars have a hollowed undersurface which may be filled with plaster 

 of Paris, and a glass hook, which is easily bent from thin glass rod, may be in- 

 serted in the liquid plaster. Naturally, this must be done some days before- 

 hand, and the plaster must be thoroughly dried out in an oven before the jar 

 is used for dehydrating. If the worker does not wish to go to this much trouble, 

 it is also easy to screw a small metal pothook into the undersurface of a plas- 

 tic screw cover for a jar of the same size. Alcohol is so hygroscopic, however, 

 that it is better to employ a glass-stoppered jar, the stopper being greased 

 with stopcock grease or petrolatum for a permanent setup. An object as coarse 

 as the one under discussion may be suspended in a loop of thread or cotton 

 directly from the hook, or, if this is not desirable, may be enclosed in a small 

 fold of cheesecloth for suspension. After 24 hours in this volume of alcohol, 

 the object will be completely penetrated by the 96 per cent alcohol and should 

 be transferred to absolute alcohol, using the same volume in a jar of similar 

 construction. It is useful to place about a quarter-inch layer of anhydrous cop- 

 per sulphate at the bottom of the absolute alcohol jar, not only to make sure 

 that the alcohol is absolute but also to indicate, as it changes to blue, when 

 this jar should be removed from service. Of the many dealcoholizing (clearing) 

 agents which may be used, the author would select benzene in the present case 

 because it is less liable to harden the circular muscles of the intestine than is 

 xylene. Since benzene is lighter than absolute alcohol, it is not possible to em- 

 ploy the hanging technique for clearing, and the object should be placed in 

 about 25 cc. of benzene, which should be changed when diffusion currents 

 no longer rise from the object. This is likely to be about six hours for an ob- 

 ject of the size under discussion, and a second bath of at least six hours 

 should be given. 



It is necessary to select the medium in which embedding is to be done. The 

 author would recommend the rubber paraffin of Hance (see p. 56) which must, 

 of course, have been prepared some time before. The melting point of this 

 medium is about 56° C. The oven should contain three stender dishes (see 

 Fig. 5) as well as a 500 cc. beaker containing about a pound of the embed- 

 ding medium. The object is removed from benzene, drained briefly on a piece 

 of filter paper, and placed in one of the stender dishes which has been filled to 

 the brim with the molten embedding medium. Under no circumstances should 

 a lid be placed on the stender dish since it is desirable that as much as pos- 

 sible of the benzene should evaporate while the process of embedding is going 

 on. After about three hours the specimen should be removed to fresh wax in 



