612 JAMES W. BARRETT. 
eye be that of a very small animal, the result has been some- 
times better. 
I have further found that this process almost always pro- 
duces some histological changes in the tissues; they are, 
however, sometimes slight. 
Infiltration with Paraffin.—This method is exceed- 
ingly useful for the preparation of sections of the eyes of 
embryos, of the eyes of very young animals, and of sections of 
eyes in those cases where the examination of the lens is not 
necessary. Its great merit lies in its simplicity. 
I have practised two methods of infiltrating. The turpentine 
process : 
a. The eyes hardened, opened, and stained, as before, are 
transferred from alcohol to oil of cloves, in which they are 
left until they are cleared; they are then soaked in pure tur- 
pentine for several hours, and are finally placed for twelve 
to forty-eight hours in paraffin, melted at a temperature not 
exceeding 50°C. The paraffin displaces the turpentine and 
permeates the crevices of the tissue. The infiltrated eye is 
then embedded in paraffin, and sections may be cut and sealed to 
the slide in the usual manner. The cement which has been most 
serviceable to me is a mixture of oil of cloves and collodion. 
It is practically impossible to stain the sections after they 
have been cut and sealed to the slide. Certain passable results 
may occasionally be obtained by the use of diffusible stains, 
but as a rule the result is disappointing. 
Unfortunately, this process nearly always ends in the total 
histological destruction of the lens (in fact too often a section 
of the lens cannot be prepared, since it instantly crumbles to 
pieces), and too frequently renders the tissues unfit for very 
minute examination. I thought that this alteration of the 
tissues was due to the high temperature of the melted paraffin, 
and I therefore obtained a paraffin which melted at 35° C., 
infiltrated the eyes with it, and then embedded in a harder 
sample. The tissue was, nevertheless, somewhat altered. I 
have, however, obtained better results by using the paraffin 
in a different manner. 
