276 PROGRESS OF MICROSCOPICAL SCIENCE. [^rum^l.^Mm^ 
Two examples of milk taken from cows on tlie fourth day of the 
disease were found to be highly charged with granular masses ; the 
milk, however, was remarkably rich in quality, having a specific gravity 
of 1034, and yielding a large proportion of cream. Diminution of the 
quantity of milk is invariably observed during the progress of any 
febrile disease ; and in foot and mouth complaint the loss is sometimes 
considerable. Cows, when suffering from the worst form of disease, 
lose nearly all their milk ; but when the attack is mild in character, 
the decrease will not be more than one-third of the usual yield. The 
average loss in a large dairy while the disease is going through the 
sheds will vary from one-third to two-thirds, according to the number 
of severe cases. As all the milk obtained is mixed, the worst milk 
will be to some extent modified by the addition of that which is less 
highly charged with morbid elements, and the whole is further diluted 
by the addition of water, which, judging from some specimens obtained 
from an establishment where the disease was known to exist among 
the cows, is sometimes added to the extent of 40 per cent. Boiling 
the milk has been recommended for the purpose of preventing or 
lessening its injurious action ; but as a matter of fact it may be stated 
that boiling does not alter the appearance of the morbid elements, nor 
does it arrest the movements of bacteria in the fluid. No changes of 
a specific kind have been observed in the blood of animals affected 
with foot and mouth disease. The blood-discs, when examined im- 
mediately after the blood is taken, will be seen to be covered with 
projecting peculiar points; but after a short time many of them 
resume the normal circular form. The white corpuscles are in 
excess, and there are also present minute circular bodies, which move 
actively ; but all these phenomena may be observed in the blood 
of animals suffering from other diseases. Numerous examinations of 
the flesh of cattle which have been destroyed while suffering from foot 
and mouth disease have been made at various times ; but no important 
morbid changes have been detected. In many specimens the peculiar 
worm-like bodies, which were found so abundantly in the muscles of 
animals dead of cattle plague, have been seen ; but seldom in large 
numbers. The meat, however, presented no indications of disease, 
and, considering that an enormous quantity of such meat has been 
consumed during the last four months, it can scarcely be imagined 
that the flesh of animals affected with foot and mouth complaint 
possesses any deleterious qualities. 
The Batio-micro-polariscoj)e. — In a paper read at a late meeting of 
the Quekett Club, Mr. J. J. Field gave the following account of this 
instrument, which he has recently constructed, and of its uses : — No 
microscopist need look very far through his collection before meeting 
with certain structures that altogether refuse to be evidenced without 
polarization ; but in such cases even polarized light is of little avail, 
unless certain exact conditions, or at all events a very near approxi- 
mation to such exact conditions, of the polarized beam in relation to 
those structures can be commanded. Indeed, I have repeatedly 
observed that when polarized light is employed in a haphazard 
manner, it may indeed paint the object with gorgeous Jmes ; but 
