ales ON ANIMAL LIFE 101 
Whalebone- Whale over 70 feet, Sibbald’s 
Whale is said to have reached 80-90, which 
is perhaps the limit. Captain Scoresby in- 
deed mentions a Rorqual no less than 120 
feet in length, but this is probably too great 
an estimate. 
COMPLEXITY OF ANIMAL STRUCTURE 
The complexity of animal structure is even 
more marvellous than their mere magnitude. 
A Caterpillar contains more than 2000 mus- 
cles. In our own body are some 2,000,000 
perspiration glands, communicating with the 
surface by ducts having a total length of some 
10 miles; while that of the arteries, veins, 
and capillaries must be very great; the blood 
contains millions of millions of corpuscles, 
each no doubt a complex structure in itself; 
the rods in the retina, which are supposed to 
be the ultimate recipient of light, are esti- 
mated at 30,000,000; and Meinert has calcu- 
lated that the gray matter of the brain is 
built up of at least 600,000,000 cells. No 
