698 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
the supply pipe it is well to have a piece of filter paper stretched 
across the mouth of the piece of tubing in the form of a diaphragm, 
and held in place by the overlapping india-rubber tubing. This pre- 
vents the possibility of the narrow part of the tube being choked up 
by any minute particles. 
Fluid 2 thus enters into the mixing bottle at an extremely slow rate 
of flow, and becomes completely diffused, at first in extremely minute 
quantity, through fluid 1. The fluid from the mixing bottle is mean- 
while entering bottle B at the same extremely slow rate, and it is 
obvious that with two fluids that readily mix, fluid 1 may be made to 
replace fluid 2 in bottle B with the required excessive slowness and 
regularity. 
In the case of some of the liquids used in fixing and preserving, it 
is not necessary to use such a precaution as this. We may substitute 
saturated solution of corrosive sublimate for sea-water without the least 
risk of damage to the most delicate structures — the specific gravity of 
the two being very nearly the same. 
Similarly distilled water may be at once substituted for osmic acid 
solution, or 1 per cent, chromic acid, or other fluid that does not differ 
at all widely from water in specific gravity. But with certain fluids the 
gradual substitution is necessary, and it is above all necessary in re- 
placing water or a watery solution by alcohol, and this, in the case of 
large specimens intended for museum purposes as well as smaller 
objects, can very conveniently be carried out by the simple apparatus 
1 have described above. 
Another method of effecting this substitution is the one devised by 
Schultze ; and this seems to possess some decided advantages, at least 
for small objects. Schultze places the objects which he wishes to trans- 
fer from water to alcohol in a tube full of water, plugged at one end, 
and closed at the other by a diaphragm of chamois skin. The tube 
is placed in a vessel of alcohol and left there until by a process of 
diffusion through the diaphragm the water in the tube becomes com- 
pletely replaced by alcohol, the same material being used for the 
diaphragm. The time which will be occupied before complete substitu- 
tion takes place will vary with the capacity of the tube and the 
diameter of its orifice ; and a series of experiments and calculations 
would have to be made before this method could be used with the 
assurance of good results. Should it be desired to have the specimens 
in absolute alcohol at the end of the process, some calcined sulphate of 
copper may be placed in the outer vessel.” 
Investigation of Blood of Amphibia.* — Dr. A. B. Macallum ex- 
perienced great difficulty in finding a reagent which would show the 
presence not only of haemoglobin, but of its antecedent, if such existed. 
Of the dyes belonging to the aromatic group of organic compounds eosin 
was the only one which was found to be useful. A reagent of great 
service was the staining fluid of Shakespeare and Noring which the 
author calls the Indigo-carmine Mixture. As he makes it, it consists of 
a mixture of equal volumes of two solutions ; one consists of carmine 
2 grm., borax 8 grm., and distilled water 100 c.c. The other is com- 
* Trans. Canadian Institute, ii. (1892) pp. 222-8. 
