152 THE OREGON 
mental capacity, it necessarily follows that there 
should bea similarity in the structural altera- 
tions induced by diseased conditions in ail kinds 
of animals, allowing, of course, for the differen- 
ces in environment, This we know to be the 
case, and it is clear that as there has been a 
gradual evolution of compiex from simple or 
ganising, it necessarily follows that the princi- 
ples of evolution ought to apply to diseased con 
ditions, if they hold good for the normal, ot 
healthy states of organisms: in plain: words then, 
that there has been an evolution of disease * fu- 
ri passer’ with the evolution of animal forms. 
For along timeit has been customary to talk of 
physiological types of diseased tissues, and my 
earlier efforts were directed to search ng among 
animals for the purpose of detecting in them the 
occurrence of tissues, which in man are found 
only under abnormal conditions. ‘he search 
was of great value to me, for the statement proved 
to be true in only a limited sense; at the same 
time however the truth of an opinion held by 
nearly a! 1 thoughtful physicians, that disease 
may in many instances be regirded as exagger- 
ated function, was forcibly illustrated, and it 
could quickly be seen, that the manifestations 
of disease were regulated by tne same laws which 
govern physiological processes in general, and 
that many conditions regarded as pathological 
in one animal and perfectly natural in anotier, 
It will be useful to illustrate this by a few con- 
crete examples. 
To take a simple case. The inside of our 
cheeks have a soft lining known as mucous 
membrane. In rare instances children have 
been born with tufts of hair growing in this sit- 
uation, This of course is purely pathological. 
A physiological type forsuch a phenomenon 
is found in the mouths of rodent 
the inside of the cheeks of rabbits, hires, porcu- 
mammals: 
pines, and the like, present natural patches of 
hairy skin. 
Again: pigment is widely d.ffused in animal 
bodies, both under natural and unnatural con- 
ditions, using the term unnatural as equivalent 
to disease: this explanation is necessiry, for dis- 
ease being controlled by natural conditions can- 
NATURALIST. 
Now, 
in the dace we notice sundry collections of black 
When ex- 
amined critically the centre of each dot contains 
a white speck. 
not logically be regarded as unnatural. 
pigment dotted among the scales. 
These collections of pigment 
are due to a parasite. In the lungs of tigers, 
lions, monkeys and sheep are found similar pig- 
mented spots around parasites. In man,horses 
and dogs, tumors of an inky black color, called 
in consequence melanotic, are occasionally met 
with, All these conditions are purely patholo- 
gical. Under normal conditions however, cut- 
tle fish (Octopus and sefia) possess an ink bag 
from which, when these animals are irritated, 
an ink-like pigment -sepia— can be ejected in 
such abundance as to color the surrounding 
water to the extent of a cubic yard or more,and 
under cover of which the cuttles escape from 
their enemies. 
( To be continued. ) 
To any one who will send the names of eight 
new subscribers to the Oregon Naturalist and 
$4.00, a copy of ‘‘ Nests and Eggs of North 
American Birds,’”’ by Oliver Davie, — Fifth edi- 
tion, — will be sent asa premium, This is the 
new edition, now in press, 700 pages, printed 
on fine laid paper and handsomely bound in 
cloth. This will be thoroughly revised, aug- 
mented, and profusely illustrated. Price, $2.25 
The Oregon Naturalist will be sent for the 
remainder of year, !ice io all new subscribers, 
