CHAPTER XXIV. 



MACERATION AND DIGESTION. 

 Maceration. 



517. 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, 

 as the cement-substances are frequently tougher than the 

 elements themselves,, so that the latter are torn and destroyed 

 in the process. In this case recourse must be had to macera- 

 tion processes, by which is 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 softening 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) admir- 

 able 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 gradu.-illy pressed down, whilst at the same 

 lime the cells of the tissue are segregated 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. 



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



