THE .ETIOLOGY OF RABIES. 
167 
finally by the adoption of one method we have been able to 
reveal the existence of certain elements which are not present in 
healthy spinal marrows. This result was attained by the use of 
the method of hardening and coloring devised by Ehrlich and 
Weigert, and by making an absolute rule to examine only per¬ 
fectly satisfactory sections, whose thickness did not exceed ah of 
a millimetre. 
“The marrows should be immersed immediately after death in 
a solution composed of 2 - 5 grm. of bichromate of potassium and 
1 grm. of sulphate of copper to 100 grm. of water. The sulphate 
of copper is important for the subsequent staining, and also 
because of its antiseptic properties, which guarantee that no new 
organisms gain access to the section during the process of harden¬ 
ing. The cord is afterward divided into short sections, so that 
they can be immersed in Weigert’s hsematoxylin solution ; they 
are then passed into absolute alcohol and oil, imbedded in paraffin, 
and a series of fine microscopical sections is made. These are then 
passed into Mayer’s fluid, decolorized in ferrocyanide of potassium, 
and mounted in Canada balsam. Similar pictures may be obtain¬ 
ed, but less clearly defined, by subjecting the small sections of the 
cords to the vapor of osmic acid, and decolorizing in a solution 
of oxalic acid before imbedding. 
“If these preparations have been decolorized with care, there 
may be seen in them groups of small globules similar to micro¬ 
cocci. These are situated sometimes in the lamella of the 
neuroglia, more rarely in the space in the cylinders between the 
portion stained deep blue and the sheath of Schwann, which is 
only tinted yellow. Sometimes these groups are found in the 
small cavities, which have a diameter less than that of the myelin 
fibers, the histological nature of which is not as yet understood. 
These granules are perfectly spherical, clearly defined, and stain¬ 
ed a deep violet color. They are arranged in a definite order, 
and do not form chaplets.* They are found in the form of a 
figure of eight (8), which indicates multiplication by division. 
Their diameter is about 0*2 of a micro-millimetre. 
“If an appropriate cultivation medium is inoculated with a 
rabid brain, a development occurs, accompanied by a slight cloudi- 
I 
