122 Annual Report for 1893 from the Principal of the 
Such are the main clinical points in connection with this disease ; 
and before describing the observations that have been made regard- 
ing it at the Veterinary College during the past year, it will be well 
to refer to the view generally held hitherto in this country regard- 
ing its pathology. 
According to the standard British text-books on veterinary 
medicine, (1) the urine in this disease contains a marked excess of 
urea ; (2) the post-mortem does not reveal serious or constant 
lesions in any of the organs ; and (3) the essence of the disease is the 
presence of large quantities of urea and allied substances in the blood. 
Repeated observations have shown that all of these views are 
erroneous. The urine does not contain an excess of urea, but it 
does contain large quantities of pigment, to which it owes its dark 
colour. The blood-plas- 
ma (the liquid in which 
the blood-cells are sus- 
pended) also contains a 
large quantity of dis- 
solved pigment. For 
such pigment there are 
only two possible sources, 
viz. the red cells of the 
blood or the red muscles 
of the body. Micro- 
scopic examination of 
the muscles that were 
rigid during the attack 
brings to light a most 
interesting lesion, which 
is illustrated in fig. 3. 
The section there repre- 
sented shows only a few 
fibres that have retained 
their normal structure 
(A ) ; these show regular 
transverse markings. But in most cases the fibres have undergone a 
serious alteration. They first lose their transverse markings, their 
substance then swells up and becomes homogeneous, and finally they 
break up into irregular fragments (B). 
That the blood-plasma in this disease contains a large excess of 
haemoglobin in solution, and that the muscles that were rigid during 
life are altered in the way described, has for a number of years 
been known to German veterinary pathologists, and two theories 
of the pathology of the disease have been based on these facts. 
The first is, that the pigment in solution in the blood-plasma is 
derived from destroyed red blood -corpuscles, and the second, that 
it is muscle pigment set free by the destruction of the fibres in the 
rigid muscles. There are several ways in which one might obtain 
evidence to show which of these views is the correct one, but 
perhaps the most obvious way would be to ascertain from time to 
Fig. 3 
