16, 3 
Taylor: Philippine Amphibia 
215 
sometimes sell for as high as 10 pesos ^ per dozen. The species 
ordinarily cultivated in the United States is the bullfrog Rana 
catesbeiana, which is the largest American species. There are 
two or three Philippine species which attain large size, one of 
which, Rana magna, approaches the size of the American bull- 
frog. There is no doubt that they could be cultivated readily 
in the swamps and marshes of the Philippines, or even in rice 
paddies, provided their enemies, snakes and large lizards, were 
partially eliminated. 
Many toads of the families Bufonidse and Engystomidse have 
poisonous secretions in the skin, which protect them from being 
eaten by some animals. Snakes, however, will eat most of the 
species. Only species of the family Ranidse should be regarded 
as of value as food for man. 
Frogs and toads, particularly in the tadpole stage, destroy 
many mosquitoes, especially during the rainy season, which is the 
breeding season for the group. The adults eat quantities of ants, 
flies, beetles, and other insects. 
REPRODUCTION ' 
Frogs, toads, and salamanders reproduce by eggs. The eggs 
are fertilized extraneously, the male clasping the female and 
remaining on her back during the process of ovulation. As the 
eggs are being extruded the seminal fluid of the male, which 
contains the sperms, escapes and flows over and about the eggs, 
which are fertilized when the sperms enter them. None of the 
Amphibia, save the csecilians, has an intromittent sexual organ. 
After a given period the young escapes from the egg and 
passes through a larval stage. During this stage the animal 
lives for the most part in the water and appears more like a 
flsh than an amphibian. In the salamanders and csecilians true 
external gills are developed. In some rare cases the larval stage 
continues during the entire life of the animal, and it breeds and 
reproduces even though it has not developed beyond that stage. 
In the genus Ichthyophis, a representative of the csecilians, the 
females place their eggs in underground holes near water. These 
eggs are about 6 by 9 millimeters in diameter, being more or 
less oval in outline. In I. glutinosus the female coils about the 
eggs, evidently for the purpose of protecting them from their 
enemies. The eggs attain a much larger size before hatching; 
the mature embryo weighs four times as much as the newly 
* One peso Philippine currency equals 50 cents United States currency. 
