THE FROG KIND. 



68$ 



agitated more than before ; the males made 

 a cioise somewhat resembling the grunting of 

 a hog; the females only keptsinking and rising 

 jnthc water. The male of the first couple eject- 

 ed the humidity with which his body was swol- 

 len, by which the water in the glass was made 

 muddy ; and he soon after quitted the female. 

 Our philosopher continued for twelve hours 

 to 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 eject- 

 ed 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 remained 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 

 thee observations it was easy to infer, that 

 the female was impregnated neither by the 

 mouth, as some philosophers imagined, nor 

 bv the excroscence at the thumbs, as was the 

 opinion of Linnasns. 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 eleven 

 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, 

 expand themselves into a round form, and 

 drop to the bottom of the water: while the 



The tadpole is furnished with a small tube beneath 

 the lower jaw, which arts as a sucker, and by menus of 

 which it can at pleasure attach itself to the under surface of 



wo. 59 & 60. 



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 dif- 

 ferent kinds of liquor. That which immedi- 

 ately surrounds the globe is clear and trans- 

 parent, and contained in its proper mem- 

 brane; that which surrounds the whole is 

 muddy and mucus. The transparent liquor 

 serves for the nourishment of the tadpole 

 from time to time ; and answers the same pur- 

 poses 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 immediate- 

 ly sink to the bottom of the water, never be- 

 ing 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 spherical form. The twenty-first day, 

 the egg is seen to open a little on one side, 

 and the beginning 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 crea- 

 tures fall to the bottom; while others remain 

 swimming in the fluid around them, while 

 their vivacity and motion is seen to increase. 

 Those which fall to the bottom remain there 

 the whole day; but having lengthened them- 

 selves 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 



aquatic plants : from these plants it can also suspend itself, 



when very young, by a kind of glutinous thread, in the 



same manner as spiders drop from the ceiling to the.grouod. 



5F 



