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 fbcatives 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 hsematoxylin, counter- 

 stained with eosin or erythrosin, Delafield's hjematoxylin, 

 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 'Vn 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. 



