74 
CHRISTIANNA 
SMITH 
I 
Il 
IIl 
Soluble in absolut 
e alcohol or ether 
Faintly refractive 
Refraction Strongly refractive] Intermediately re- 
fractive 
Effect of fixatives | Little affected by} Gradually  disap- 
and postmortem 
changes 
fixatives (except 
formalin) or post- 
mortem changes 
pear under the 
influence of fixing 
agents, and post- 
mortem changes. 
Preserved by 
Bell’s 10 per 
cent dichromate 
method 
Staining and fixing reactions 
1. Searlet red, fresh | Intensely stained | Less 
material 
2. Sudan III after! Annular form of 
Bell 
3. Osmie acid 
droplet 
Stain black 
intensely 
stained 
Stain brown or not 
colored 
Chemical composi- | Essentially olein 
tion 
some other fatty 
substance, e.g., 
cholesterol 
Disappear in most 
fixing agents, 
such as formalin 
and postmortem 
changes. Pre- 
served by Bell’s 
10 per cent di- 
chromate method 
Faintly stained 
Solid red droplet 
Not stained 
Olein mixed with | Low melting fat 
(butyrin) 
after death. Bell (11) and Bullard (12) emphasized the 
necessity of using fresh material if all fat present was to be 
demonstrated, and Policard and Garnier (’05) found that renal 
cells underwent postmortem changes fifteen minutes after death. 
In the study of the lipoids, three kinds of material are usually 
employed: fresh tissue; that which has been fixed in a dichromate 
solution where the reduction of the dichromate renders the fat 
insoluble and stainable with hematoxylin, and that which has 
been preserved in osmic acid, which certain lipoids will reduce 
with subsequent blackening of them. In order to get as complete 
an idea as possible of the lipoid content of cells, these three 
methods should be used, one as a check for the other. The 
