

976 The American Naturalist. [November, 
Animals. Muscles. Bodies. Ratios n Muscles o Body 
mate 
Woodchuck, -1 1b.4 oza | 5 lbs. 1:4 
it, Ooo 23 02. 1:2 
Gray squirrel, 12 oz. 25 02. it? 
Black squirrel, 11 oz. 24 OZ. eae 
Skunk, 13 02, 3 lbs. 10 oz. 1:4% 
Animals. Bones. Bodies. Ratios of Bones to Body 
: approximate). 
Woodchuck, tib, 5 lbs. E; 
Rabbit, 5 OZ. 23 OZ. 3 4 y 
Gray squirrel, 4 02. 25 02. 
Black squirrel, 4 Oz. 24 0z. I: n 
Skunk, IT öz. 3 lbs. 10 oz. 15 
Animals. Viscera. Bodies. Ratios of Viscera to Body 
i pproximate). 
Woodchuck, 1 lb. 12 oz. 5 lbs. 1:3 
Rabbit, 5 02. 23 oz, 1:4% 
Gray squirrel, 4 02. 25 úZ. Lie 
Black squirrel, 5 02. 24 Oz. 1:5 
5 ig of: > 3 lbs. 10 07; 1:4 
The fact which impresses us most about these figures is that the 
relative proportions of the tissues here considered are far from con- 
stant in the same and in different animals. The right-hand figures 
in the column of ratios are well calculated to emphasize this fact. 
The tegumentary, bony, nutrient, and motor tissues do not each 
have equal weights in the same animal, and the ratio of their 
weights to the body-weights are not the same in different animals. 
For example, the ratio of the weights of the skin to the body vary 
all the way from 1: 8 in the rabbit to 1: 414 in the skunk; the 
ratios of the muscles from 1:2 in the rabbit and squirrels to 
1:4% in the skunk; the ratios of bones from I :4% in the rab- 
bit to 1:6 in the squirrels; and the ratios of the viscera from 1: 3 
in the woodchuck to 1:6 in the gray squirrel. Thus it appears 
that variations of one-half are not uncommon for the same tissue 
in different animals, and much profounder differences exist in the 
weights of different tissues of the same animal. Without doubt, 
more extensive dissections would reveal even greater extremes — 
in the quantities of tissue in other mammals and in verte- — 
raies Sees ieee the 1 nerves and the brain oe 7 


