186 THE MIcROSCcOPE. 
or stroma-fibrin and a fibrillar or plasma-fibrin must be recog- 
nized, the former being identical with Weigert’s coagulation - 
necrosis. 
The conclusions drawn by Kemp regarding the relation of 
plaques to coagulation are: 1. When the blood is drawn the 
plaques break down almost immediately. This is not true of 
any other element of the blood. 2. The breaking down of the 
plaques is intimately connected, in times at least, with the clot- 
ting of the blood. 38. The connection between the breaking 
down of the plaques and the coagulation of the blood is not 
histological, but chemical—i. ¢., the plaques appear to give up a 
soluble substance which is active in coagulation. 4. Theactive 
agent in question is most probably #brin-ferment. 5. Fibrin is 
deposited histologically independent of any of the cellular ele- 
ments of the blood. 6. When the clot is very scant fibrin is de- 
posited as long, needle-shaped, crystal-like bodies.—Editorial 
from the Journal of the American Medical Association. 
ORIGIN AND MICROSCOPICAL STRUCTURE OF COAL. 
After a brief conversation at the tea-table, the host intro- 
duced the subject of the “ Origin and Microscopical Structure of 
Coal.” Two large “restoration pictures” or landscapes of the 
coal period showed in their living condition the peculiar plants 
and trees now found fossil in coal mines, being represented as 
luxuriating in the moist and swampy levels. Nearly the whole 
of the present area of the British Isles, with the exception of 
the northern half of Scotland, was shown as thus occupied. 
According to Sir Joseph Hooker, the climate was not sub- 
tropical, but moist and equable, like that of many islands of 
the Southern Hemisphere to-day. A companion map showed 
the very few spots in which the widely-deposited coal beds 
have survived the wasting atmospheric and other cosmical 
agents. Passing from the macroscopic to the microscopic, the 
speaker said that in the year 1870 Professor Huxley somewhat 
startled the scientific public by his memorable paper on the 
formation of coal, and his postulate that ordinary English and 
Scotch coal is made up chiefly of microscopic spores and spore 
cases, not unlike such as we see on the under surface of a 
bracken leaf. These minute organisms in their primary or de- 
