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NOTE ON CARBOLIC ACID AS A FIXATIVE FOR 
HISTOLOaiCAL PREPARATIONS. 
By C. Lawrence Herman. 
During 1912 whilst working in the Laboratory for Experimental Patho- 
logy in Vienna, I was led to investigate the condition of the colloid contents 
of the thyroid follicle, especially when subjected to different methods of 
fixation. 
Important deductions had been drawn from the appearance of the colloid 
as seen under the microscope as to its behaviour to stains, and more especially 
as to being more or less fluid under certain conditions. 
This applied particularly to pathological changes, and I wished to 
determine in how far this was caused by the methods of preparation 
employed. 
I accordingly examined sections of the thyroid after fixation by a large- 
number of different substances in varying dilutions. 
On the outbreak of the war I had to leave Vienna very hurriedly and 
my notes and records had to be left behind and I fear have been lost. 
However, without going into details at present, I may say in general L 
found that most of the fixatives used, including the most frequently 
employed and customary ones, presented some or other disadvantage, either 
causing shrinking or vacuolation, or the solution of the colloid wholly or in 
part ; while several interfered with the staining especially of the colloid. 
In the case of carbolic acid, however, a good and complete fixation was 
obtained without shrinking or the production of vacuoles and with very 
good optical differentiation of cell structures. Moreover, the staining 
reaction was not interfered with. 
On the contrary the various stains used were taken up readily and 
completely. 
Further application of this method to various tissues and organs — the 
liver, stomach, the abdominal organs generally, and the central nervous 
system — gave exceedingly gratifying results, especially in cases where rapid 
penetration and fixation is of advantage, such, for example, as the rat's 
testicle. 
