380 



HISTORY OF FROGS, LIZARDS, AND SERPENTS. 



observe whether the female would cast her 

 spawn ; but finding her tardy, he dissected 

 both her and the male : in the latter, the sper- 

 matic vessels were quite empty, as might na- 

 turally have been supposed ; but for the fe- 

 male, her spawn still remained in her body. 

 Upon its being extracted, and put into water, 

 it perished without producing any animal 

 whatever. From hence he justly concluded, 

 that it required that the eggs should be ejected 

 from the body of the female before they could 

 be at all prolific. In another pair the male 

 quitted the female, who did not eject her 

 spawn till sixteen days after ; and these, like 

 the former, came to nothing. But it was very 

 different with some of the rest. The females 

 ejected their spawn while the male still re- 

 mained in his station, and impregnated the 

 masses at different intervals as they fell from 

 her ; and these all brought forth animals in 

 the usual course of generation. From these 

 observations it was easy to infer, that the fe- 

 male was impregnated neither by the mouth, 

 as some philosophers imagined, nor by the 

 excrescence at the thumbs, as was the opinion 

 of Linnaeus, but by the inspersion of the male 

 seminal fluid upon the eggs, as they proceeded 

 from the body. 



A single female produces from six to ele- 

 ven hundred eggs at a time ; and, in general, 

 she throws them all out" together by a single 

 effort; though sometimes she is an hour in 

 performing this task. While she is thus 

 bringing forth, it may be observed that the 

 male acts the part of a midwife, and promotes 

 the expulsion of the eggs by working with his 

 thumbs, and compressing the female's body 

 more closely. The eggs which were com- 

 pressed in the womb, upon being emitted, ex- 

 pand themselves into a round form, and drop 

 to the bottom of the water ; while the male 

 swims off, and strikes with his arms as usual, 

 though they had continued so long in a state 

 of violent contraction. 



The egg, or little black globe, which pro- 

 duces a tadpole, is surrounded with two differ- 

 ent kinds of liquor. That which immediately 

 surrounds the globe is clear and transparent, 



mouth has acquired movable lips, and has changed its 

 position from the inferior part of the head to near the 

 extremity, and the little creature which has hitherto de- 

 rived its sustenance either from its own resources or by 

 absorption, now seeks its food amid softened and decom- 

 posing vegetable matter. The caudal web (fig. 8) has, 

 therefore, become considerably developed, and serves for 

 very rapid as well as varied locomotion. The colour of 

 the body, too, has undergone a considerable change, hav- 

 ing become of a soft olive green, the abdomen being 

 dotted with golden yellow. The Tadpole now undergoes 

 but little change in its external form for a considerable 

 time, but increases rapidly in bulk, and by and by a lit- 

 tle tubercle appears on each side of the vent, which is 

 the rudiment of the posterior extremity. Bell's History 

 of British Reptiles. 



and is contained in its proper membrane; that 

 which surrounds the whole is muddy and mu- 

 cous. The transparent liquor serves for the 

 nourishment of the tadpole from time to time ; 

 and answers the same purposes that the white 

 of the egg does to birds. The tadpoles, when 

 this membrane is broken, are found to adhere 

 with their mouth to part of it ; and when they 

 get free, they immediately sink to the bottom 

 of the water, never being able to get to the 

 top after, while they continue in their tadpole 

 form. 



But to return When the spawn is emitted 

 and impregnated by the male, it drops, as was 

 said, to the bottom, and there the white quickly 

 and sensibly increases. The eggs, which, 

 during the four first hours, suffer no perceptible 

 change, begin then to enlarge and grow 

 lighter ; by which means they mount to the 

 surface of the water. At the end of eight 

 hours the white in which they swim grows 

 thicker, the eggs lose their blackness, and, as 

 they increase in size, somewhat of their spher- 

 ical form. The twenty-first day, the egg is 

 seen to open a little on one side, and the be- 

 ginning of a tail to peep out, which becomes 

 more and more distinct every day. The 

 thirty-ninth day the little animal begins to 

 have motion ; it moves at intervals its tail ; 

 and it is perceived that the liquor in which it 

 is circumfused serves it for nourishment. In 

 two days more some of these little creatures 

 fall to the bottom ; while others remain swim- 

 ming in the fluid around them, while their vi. 

 vacity and motion is seen to increase. Those 

 which fall to the bottom remain there the 

 whole day ; but having lengthened themselves 

 a little, for hitherto they are doubled up, they 

 mount, at intervals, to the mucus which they 

 had quitted, and are seen to feed upon it with 

 great vivacity. The next day they acquire 

 their tadpole form. 1 In three days more they 

 are perceived to have two little fringes, that 

 serve as fins beneath the head ; and these, in 

 four days after, assume a more perfect form. 

 It is then, also, that they are seen to feed very 

 greedily upon the pond-weed with which they 

 are to be supplied; and, leaving their for- 

 mer food, on this they continue to subsist 

 till they arrive at maturity. When they 

 come to be ninety-two days old, two small 

 feet are seen beginning to bourgeon near 

 the tail: and the head appears to be se- 

 parate from the body. The next day the legs 

 are considerably enlarged : four days after 



1 The tadpole is furnished with a small tube beneath 

 the lower jaw, which acts as a sucker, and by means of 

 which it can, at pleasure, attach itself to the under sur- 

 face of aquatic plants: from these plants it can also sus- 

 pend itself, when very young, by a kind of glutinous 

 thread, in the same manner as spiders drop from the 

 veiling to the ground. 



