42 
TTe studied a large number of pigs in which death occurred T\dthin 
thirty minutes of the second injection of serum; also, a moderate 
number wliich were killed by chloroform or otherwise from one to 
four hours after the second injection. 
We are indebted to our colleague Dr. W. W. Wller, United States 
Public Health and Marine-Hospital Service, for the foUovdng studies 
upon the post-mortem appearances and patholog}- of the tissues of 
guinea pigs dead of anaphylaxis. 
The most noticeable lesion to the naked eye is the marked dilata- 
tion of the small veins and capillaries of the body, but most noticeable 
in those of the abdominal Hscera. Associated with this in about 25 
per cent of the cases are hemorrhages in the mucosa of the stomach 
and, more rarely, of the intestines. Minute hemorrhages 1 mm. in 
size are occasional^ observed on the surface of the lungs; no hemor- 
rhages of the heart muscle, spleen, pericardium, or striped muscle, as 
described by Gay and Southard, have been seen. 
For microscopic study the tissues from 16 guinea pigs were utilized. 
These pigs had received the second dose of serum in three ways, viz, 
by subcutaneous, intraperitoneal, and intracranial injection. Mate- 
rial was selected from all the viscera and from the striped muscles 
and nervous systems. Particular attention was given to the study of 
tissues for the fatty changes described by Gay and Southard. For 
this purpose sections made with the freezing microtome were used to a 
great extent, as it is generally recognized that fresh material is supe- 
rior to that prepared and sectioned in the customary way in celloidin 
and paraffin, although it must be admitted, as Gay and Southard 
contend, that such preparations are not as permanent or suitable 
for micro-photographic purposes. For a general study of microscopic 
changes tissues were fixed in 10 per cent formalin, in formalin and 
alcohol (5 and 85 per cent), and Zenker. 
For fatty degeneration, fresh tissue and tissue fixed for twenty- 
four hours in 5 to 10 per cent watery solution of formalin was used 
and sectioned with the freezing microtome; for nerve tissue, formalin 
5 to 10 per cent, Orth’s fluid, and Muller’s fluid. 
As a stain for general purposes, hematoxylin and eosin were used. 
For staining fat, Marchi’s method was carried out as follows: Fixa- 
tion in 10 per cent formalin and Muller’s fluid six to ten days, in 
Marchi’s mixture six to ten days; kept throughout in the dark; then 
washed twenty-three hours in running water ; hardened in alcohol and 
ether celloidin as quickly as possible. Clove oil celloidin was not used, 
as it causes general blackening. 
For frozen sections of tissue fixed in 10 per centiormalin for twenty- 
four hours, the admirable method so highly recommended by Schmorl 
was used, viz, sections placed in Marchi fluid in closed vessels in the 
