OF DENISON university. 
37 
tions mounted in balsam. Several hundred such sections were pre_ 
pared and studied by the method of geometric reconstruction from 
camera drawings and measurements. 
The chrom-acetic solution appears to us to have decided advan- 
tages over any other fluid used. For some brains it should be consid- 
erably more dilute than the standard advised by Fob ^ The most gen- 
erally satisfactory stain is aqueous haematoxylin with the possible ex- 
ception of a new stain, an account of which is at present reserved. 
Alum-cochineal ranks next and, although it does not preserve the fine 
histological details and causes a shrinking of cells and delicate organs 
generally, it has the gr'eat advantage of being adapted for the staining 
of fragments in toto, thus enabling one to fix the sections upon the 
slide at once, obviating the danger of loss as well as avoiding the great 
labor involved in the usual haematoxylin method. The ordinary car- 
mine stains are relatively useless as are the alcohol solutions of haema- 
toxylin, etc. 
Analine blue-black has many of the good properties of haematoxylin 
but seems less desirable on the whole. A solution of methyl blue in 
oil of cloves promised well, but it was found impracticable in actual 
practice. So far as our experiments went the mingling of stains with 
Mueller’s fluid proved unsatisfactory. 
In some cases alum-cochineal serves to differentiate the fibre tracts 
very perfectly, but those preparations are less perfect respecting the 
cells. In fact no reagent was found serving both purposes equally. 
We have preferred, therefore, the use of a reagent which alters the 
natural relations as little as possible and permits the tracing of what 
may be confidently regarded as the normal connections albeit at great 
expense of patience and time. Successfully stained haematoxylin prep- 
arations do this. The various methods of staining fibres only, although 
undoubtedly of the highest value, do not prove adapted for the minu- 
ter work of tracing cells in their mutual relations. Ours has been the 
common fate. It has not infrequently happened that the same process, 
applied to two entirely similar brains has resulted in failure in one 
case and success in another. Thus far no infallible technique has been 
discovered. The statements made on the basis of the few specimens.. 
studied must remain open to the criticism of subsequent study. 
Previous to the sectioning, as already said, several localization exper- 
iments were made both by electrical stimulation and extirpation. The 
first specimen was a male of Arctomys moiiax, the same specimen which 
