No. 378.] REVIEWS OF RECENT LITERATURE. 437 
lying concealed by day. After the middle of summer their appetites 
grow less keen, and as autumn comes on they begin to leave the 
special hunting fields that each has held for itself, and to migrate, 
singly, toward the ponds and lakes. It is, however, only the sexu- 
ally mature animals, four or five or more years of age, that thus 
migrate ; the young ones remain. The adults pass the winter con- 
cealed about the shores or in the mud at the bottom of the ponds, 
and awake from the dormant state when the early spring thaws out 
the ice. This occurs in March or February in the lowlands, but high 
in the mountains perhaps not until the middle of summer. 
The awakened frogs congregate in great numbers and fall an easy 
prey to the greatest of all their numerous enemies, man ; before they 
were decimated by wholesale slaughter at this, their breeding season, 
a single fisherman might take 1500 frogs in a single day. 
The males, which we infer are much more numerous than the 
females, clasp the females and passively suffer themselves to be 
carried about in the water, or even upon land, for several days — three 
to thirty, in different places and seasons. Whether the males use 
their vocal organs to produce their “ purring” noise or not seems to 
depend upon the temperature, and their use in warm weather indi- 
cates, the author thinks, a cat-like state of content. In cold seasons 
these sounds may not be heard, though breeding continues as 
usual. 
The actual spawning is accompanied by a maximum of excitement 
when the females, covered by a struggling mass of males, sink to 
the bottom of the ponds and there deposit their eggs. Each egg is 
1% to 2 mm. in diameter, black above and white below, and envel- 
oped in a lump of jelly 4 mm. in diameter. The eggs deposited by 
a female form a cluster about as large as a hen’s egg, and these 
clusters stick together so that a gelatinous layer may be formed on 
the bottom of the pond, extending, in some cases, as a band a meter 
wide all along the shore. 
This breeding season lasts on the average 134 days, from the first 
awakening to the completion of spawning, and during that time the 
frogs take no food — unless, sometimes, their skins ! The skin 
comes off in shreds, in the water, at this season, and is shed again 
three times during the year. In these moltings the animal may eat 
its own skin. 
When the eggs are laid and fertilized, the frogs all leave the ponds 
suddenly in a single night and gradually return to summer hunting 
grounds far from the water. 
