2 Wee 
1886.] —— Mieroscopy. | 315 
passed through linen. This fluid may be kept for months, and is 
readily thinned to any desired consistency by the addition of 
water. Before using, it should be tested with alcohol. A small 
quantity is placed in a test-tube, and then a little alcohol added. 
he fluid is at once changed to a solid mass of double the origi- 
nal volume, and this mass is insoluble in water. 
Thus the whole process consists in this: that borax and gum 
arabic form together an insoluble colloid mass; by pressure 
through linen, with water added, the mass passes into a fluid con- 
dition which can be diluted to any extent with water ; after injec- 
tion and immersion of the preparation in alcohol, it again assumes 
a colloid condition in which it is insoluble in water. 
The mass thus prepared may be colored with finely powdered 
carmine, or with other coloring substances ; only cobalt and cad- » 
mium are to be avoided. 
_ This mass is especially recommended for macroscopic injec- 
tions, and for the injection of lymphatic spaces. The injected 
vessels do not become hard, and the mass does not escape from 
ruptured points. During dissection the preparation should be 
covered with alcohol. 
n case it becomes desirable to dissolve the injected mass from 
any part of the vessels, this can be accomplished by dropping di- 
lute acetic acid upon it. 
The preparation can be rendered transparent by first washing 
with water, and then soaking in glycerine. Treatment with alco- 
hol again restores the opacity of the preparation. 
METHOD or KILLING GrEpHyrea—According to Apel! the 
Ph wen v Biman, E O a AE E eee g 
Osphate of potassium Soe 
a OE Westen E O ck ona ce swpiv ode) tomers SE 
led water... oog nts 
ss. Zool., XLII, H. 3, p- 461, 1885.. 
ik. Anat., xxv, H. 4, p- 445, Oct., 1885- 
