190 PREPARATION AND MOUNTING 
the liquid should be forced into it until a slight paring of 
the hoof shows the colour in the fine channels, there. 
Perhaps one of the most beautiful and interesting objects is 
the skin or section of a cat’s tongue. On examination we 
shall readily learn the reason why we feel such a roughness 
when we allow the cat to apply her tongue to our hands. 
In appearance we shall be almost ready to say that there is 
no little resemblance in the arrangement betwixt this tongue 
and those of the molluscs already described. The liver of a 
rabbit or any other animal is an easy and beautiful object 
for injection. Sections made with Valentin’s knife, and 
mounted in balsam, are not at all difficult, and worth double 
the time they occupy. | 
35. When the lungs of small animals are injected, the 
finest fluid must be used, as some of the capillaries are so 
small that it is not an easy matter to fill them properly. 
And before entering upon these subjects, a certain pro- 
ficiency in the mode of using the syringe, &c., should be 
obtained by practising upon simpler parts. 
36. No subjects are more difficult to inject than fish, 
owing to the extreme softness of their tissues. Mr. Hogg 
recommends the tail of the fish to be cut off, and the pipe 
to be put into the divided vessel which lies just beneath the 
spinal column; by which method beautiful injections may 
be made. The gills, however, are the most interesting part 
as microscopic objects. 
37. These instructions may seem very imperfect to those 
who have had much experience in this branch; but they 
will remember that their own knowledge was not gained 
from any written descriptions, but was forced upon them 
by frequent failures, some of which probably were very dis- 
heartening. As I before stated, it is very difficult (if not 
impossible) to accomplish much without some knowledge of 
anatomy. 
38. I may here mention that the transparent injections 
sent over from the Continent are beautifully executed by 
Hyrtl of Vienna (who states that the injected fluid is com- 
