Ranidae 



the moss and dead leaves. The water presents a rather deso- 

 late expanse, for it is too early for the appearance of much green. 

 All seems silent as we approach. We walk on the firm foun- 

 dation made by tangled sweet flag roots until we are at the very 

 edge of the water. As we listen and watch, low, moaning, or 

 grunting sounds proceed from everywhere about us. The pond 

 is filled with Leopard Frogs. We can see their heads, with the 

 bright eyes and distended ear-like vocal pouches protruding 

 above the water. It is impossible to make one hear these talk- 

 ing voices unless he is already famiUar with them. To say that 

 the sound is low-pitched, throaty, and vibrant does not bring it 

 to one's ears. The sounds are produced both by the male and by 

 the female. Either will make the sounds when taken into the 

 hand. 



The eggs are laid in masses in the shallow water. They 

 may be attached to sticks and grasses or left free in the water. 

 Those drawn and described were laid on the morning of April 

 9th by a frog brought from the pond two days previous. They 

 were attached to a fern leaf that bent over the water. The 

 whole laying was in one mass about five inches in diameter and 

 two and a half inches thick, which contained between five thousand 

 and six thousand eggs. Each egg is very small (i^ mm. in 

 diameter) and velvety black in colour. The eggs are so close 

 together that the entire mass is dark-coloured, notwithstanding 

 the fact that each is surrounded by a perfectly transparent 

 sphere of gelatinous substance — (see Figs. 246 and 247) — three 

 concentric spheres^ in fact. This substance is so transparent 

 that it does not prevent our watching the process of develop- 

 ment. If we look closely at the eggs, we discover that they 

 are black above only, and that the lower side — about one- 

 third of the entire surface — is creamy white in colour. The 

 egg contains not only the germ of the future frog, but yolk for 

 its growth. The white lower part of the egg consists wholly 

 of this food yolk. 



Development begins within two or three hours after the 

 eggs are laid. To the naked eye the change seems slight for the 

 first two days. It begins by the egg becoming slightly larger. 

 The black spreads until the visible white portion becomes no 

 larger than a pin-point. However, if we increase the power of 

 our eyes ever so little by the use of a magnifying-glass of any 



176 



