INTRODUCTION. xxi 



As the hearts and brains of most of the subjects selected 

 are small, similar preparations from larger types are very 

 valuable for demonstration ; for instance, the monitor or 

 iguana, the goose or turkey, and the dog, sheep, or even 

 horse. It will, of course, be all the better if some of these 

 structures — especially a larger mammalian brain than the 

 Rabbit's — can be dissected by the students themselves as 

 supplementary subjects. 



Dissections of large hearts for demonstration may be 

 prepared by the glycerine jelly process described on p. 

 2 ;i the various structures are more readily pointed out on 

 such preparations than on those kept in alcohol : they may 

 be made still clearer by colouring the different parts. 



The larger brains are best prepared by Giacomini's 

 method : the organ is placed in a saturated solution of zinc 

 chloride, and then, after removal of the pia mater, in strong 

 alcohol, which should be renewed at least once. When 

 thoroughly hardened it is transferred to strong glycerine, and 

 retained therein until thoroughly permeated : this is shown 

 by its sinking in the fluid. The brain is then removed from 

 the glycerine, drained thoroughly, and, after a time, sized and 

 varnished. Any dissections which may be required are made 

 before placing in glycerine. 



1 Since writing that description I find that the objects should be 

 well haidened in alcohol before being placed in the glycerine fluid ; 

 that it is best to substitute o-oj parts of a concentrated solution" of 

 phenol for the corrosive sublimate ; and that the specimens are best 

 finished by varnishing, after one or two coats of size, with common 

 oak-varnish. 



