48 THE BIOLOGY OF THE FROG CHAP 



found clasping different parts of the body of one female, 

 forming masses, " Begattungsklumpen," in the midst of 

 which the female can scarcely be seen. Males will often 

 clasp females which are dead, or females of another species, 

 or even toads. The males of Rana fusca have been observed 

 clasping carp and being carried around by the fish, which 

 were unable to divest themselves of their burden. The eyes 

 of many of these fishes are destroyed by the thumbs of the 

 clasping frogs. Males will usually clasp one's finger, or almost 

 any object they can seize, although they will not as a rule 

 retain hold of objects other than female frogs for a very 

 long time. The clasping instinct to a large extent over- 

 comes fear. A frog which will make violent efforts to escape 

 from the hands will often hold to one's finger and entirely 

 desist from its efforts to escape during the period of copula- 

 tion. The clasping instinct is so strong that the animal may 

 be severely injured without showing any diminution of its 

 ardor. The body of a male frog may even be cut in two in 

 the middle and the fore part will still cling tenaciously to the 

 female for hours, only desisting when the creature becomes 

 so weak from loss of blood that it can no longer retain its 

 position. 



Egg- Laying and Fertilization.- -The extrusion of eggs 

 usually occurs only after the male has clasped the female 

 for several days. The eggs, which are discharged from the 

 ovaries rather slowly, are conveyed from the body cavity into 

 the oviduct, through which they pass into the uteri, where 

 they finally all collect, distending the thin walls of these 

 organs to an enormous degree. As Spallanzani discovered 

 long ago, females killed in the first part of the breeding sea- 

 son have most of the eggs still in the ovary. Later many 

 eggs are found in their passage down the oviduct, although 

 they are not often met with in the body cavity. Females 



