BY WILLIAM A. HASWELL, M.A., B.SC. 277 



become much more rapidly coloured when treated in another way. 

 It will, therefore, be found necessary, in order to insure good 

 specimens of all the organs, to take several pieces of each prepared 

 in different ways and subject them all to the same process of 

 staining, or else, taking several pieces of each specimen, to subject 

 each of them to the action of the staining fluid for a diff"erent 

 interval. The results obtained by this method excel, in my opinion, 

 in the definiteness of the cell-outlines, and the distinctness of the 

 differentiation of the tissues any that can be obtained by any of 

 the ordinary process of staining capable of being carried out in a 



EMBEDDING IN PARRAFIN. 



Specimens of animals or of organs stained as above described enhloc 

 and afterwards treated with bichromate of potash, require, after 

 soaking for a few minutes in distilled water, to be treated with strong 

 alcohol for several days — absolute alcohol being used for at least the 

 last two days — in order completely to remove the water with which 

 they have become saturated. As in staining so also in the 

 embedding both time and material are saved by preparing a large 

 number of specimens— say twenty or more — at one time. The 

 alcohol is then replaced by chloroform. If the objects are delicate 

 and complicated, this will be very conveniently and thoroughly 

 effected by using some such contrivance as the chloroform 

 box which I employ. This is an oblong brass box divided 

 internally by a vertical partition, which does not reach the 

 bottom, but leaves an opening of three-quarters of an inch, 

 into two compartments. Chloroform with a slight admixture of 

 sulphuric ether is poui'ed into the box until it rises a little above 

 the lower border of the vertical partition. Absolute alcohol is 

 gently poured in by means of a pipette on the surface of the 

 chloroform in one of the compartments ; the objects are placed in 

 this, and, as they become saturated with the chloroform, they sink 

 down until they drift through below the partition into the other 

 compartment, which contains only the mixture of chloroform and 

 ether. From this they can be taken out without disturbing the 



