278 Phillips on a Comparative Study of the 
intra-vitam staining), methyl violet, gentian violet, picro- 
carmine, borax carmine and carbol fuchsin with the use of 
bacteriological methods of mordanting. Of these methods, 
fixing with Hermann’s fluid, chromacetic acid or picro-sul- 
phuric acid seemed to give the best results, and were the prin-- 
cipal ones used, though all fixatives were used in determining 
each point. It is no easy matter to determine what fixatives 
to use and what stains to follow them with. One stain will 
work well with one fixative, or after a certain kind of treat- 
ment, while it will absolutely refuse to stain at all with 
some other fixative. This fact has seemingly been another 
cause for much confusion in the past. Alcohol was largely 
used for fixing the materials for micro-chemical experi- 
ments. The stains that gave the best and most constant 
results were iron-ammonia-alum hematoxylin, counter- 
stained with eosin or erythrosin, Delafield’s haematoxylin, 
intra-vitam staining with methyl blue, carbol fuchsin, eosin 
and safranin with gentian violet. 
In fixing and staining the organisms, a method that 
might be termed “en masse fixing or staining’’ was followed. 
A considerable mass of the organism was taken from the 
original culture and placed immediately in the fixing fluid, 
where it was allowed to remain the required length of time. 
It was then transferred “en masse’ to water where any adher- 
ing dirt particles and the fixing fluids were washed away. 
When thoroughly washed the mass was placed in the stain- 
ing fluids, or, if sections were to be cut, imbedded in par- 
affin in the usual manner and sections cut from one to two 
microns in thickness. However, it must be remarked that 
sections revealed very little that could not be seen equally 
as well in the uncut object. A difficulty arose from shrink- 
age of the cell contents in the imbedding process, which 
could only be overcome by very gradually passing the organ- 
isms from one strength of alcohol to another, the grades not 
exceeding 7 per cent. to 10 per cent. at a time. Special care 
had to be taken in passing from absolute alcohol to oil of 
cedar, else artifacts were sure to form. 
