282 MACE RATION AND DIGESTION. 



CHAPTER XXIII. 



MACERATION AND DIGESTION. 



Maceration. 



522. Methods of Dissociation. It is sometimes necessary, in 

 order to obtain a complete knowledge of the forms of the 

 elements of a tissue, that the elements be artificially separated 

 from their place in the tissue and separately studied after 

 they have been isolated both from neighbouring elements and 

 from any interstitial cement-substances that may be present 

 in the tissue. Simple teasing with needles is often insufficient 

 to effect the desired isolation, as the cement-substances are 

 often tougher than the elements themselves, so that the latter 

 are torn and destroyed in the process. In this case recourse 

 must be had to maceration processes, by which is here meant 

 treatment with media which have the property of dissolving 

 or at least softening the cement-substances or the elements 

 of the tissue that it is not wished to study, whilst preserving 

 the forms of those it is desired to isolate. When this soften- 

 ing has been effected the isolation is completed by teasing, 

 or by agitation with liquid in a test-tube, or by the method 

 of tapping, which last gives in many cases (many epithelia, 

 for instance) admirable results which could not be attained 

 in any other way. The macerated tissue is placed on a 

 slide and covered with a thin glass cover supported at the 

 corners on four little feet made of pellets of soft wax. By 

 tapping the cover with a needle it is now gradually pressed 

 down, whilst at the same time the cells of the tissue are segre- 

 gated by the repeated shocks. When the segregation has 

 proceeded far enough, mounting medium may be added, and 

 the mount closed. 



The student will do well not to neglect this simple method, 

 which is one that it is most important to be acquainted with. 



A good material for making wax, feet is obtained (VossELER, 



