DEVELOPMENT OF GERMINAL LAYERS IN MAMMALS. 373 
or to the action of the reagents used in the preservation and 
staining processes. 
After the pregnant female had been killed with chloroform 
the uterus was removed by cutting through the broad ligaments 
and the upper part of the vagina. The whole uterus was then 
immersed in either picro-sulphuric, picro-nitric, or picro-hydro- 
chloric solution, in which it was left for an amount of time 
which varied with the size of the object, from a few hours in 
the case of small specimens up to two days in the case of large 
embryos. The acid was removed from the specimens by 
methylated spirit; the uterus was then placed in borax 
carmine solution, from which it was transferred to acidulated 
alcohol. 
After the completion of the staining the uterus was cut into 
segments corresponding to the contained ova, and the segments 
were passed through absolute alcohol and turpentine into 
paraffin, in which they were embedded. The sections of the 
segments, cut by the rocking microtome, were cemented to the 
slide by collodion and oil of cloves; they were cleared in tur- 
pentine and mounted in Canada balsam. 
The sections were made in three planes: 
1. Transversely to the long axis of the uterus. 
2. Parallel to the long axis of the uterus, but at right angles 
to the plane of the broad ligament. 
3. Parallel to the long axis of the uterus and the broad 
ligament. 
In their relation to the uterus as it lies in the body these 
sections may be termed respectively— 
(1) Vertical- transverse. 
(2) Horizontal-longitudinal or coronal. 
(3) Vertical-longitudinal or sagittal. 
The first and second series were the most useful, especially 
in the very early stages. 
VOL, XXXIII, PART III.—NEW SER. cc 
