HARDWICKE'S SCIENCE-GOSSIP. 



75 



THE NATURAL HISTORY OF THE TOAD. 

 By J. Arthur Eisdell. 

 No. II. 



THE colours of the toad are liable to some varia- 

 tion : the upper parts are of a dirty lurid colour, 

 blackish or brown, with sometimes a slight greenish 

 tinge. You will notice the greenish tinge in the 

 under skin from which the external cuticle has been 

 removed ; its under parts are of a dirty yellowish 

 white colour, sometimes spotted with black. Its 

 head is flat on the top, its brain being small ; you 

 will be able to see that there is but little room for its 

 development. Above the eyes there is a slight pro- 

 tuberance studded with pores, this protuberance is a 

 large collection of the follicular glands before men- 

 tioned. The toad has no teeth. Its quickest move- 

 ment is an imperfect leap, but its usual pace is a kind 

 of crawl. On being alarmed or threatened with 

 danger it stops, swells its body, and on its being 

 handled the arid secretion before mentioned exudes 

 from the follicles, and a discharge of limpid water 

 out of the vent takes place. 



The toad is a voracious creature, feeding upon slugs, 

 worms, grubs, and insects of various kinds, and for 

 this reason is very useful in gardens. Bell says that 

 the toad refuses food which is not living, and will 

 only take it at the moment when it is in motion. 



When about to feed the toad remains motionless 

 with its eyes turned directly forward upon the object 

 and the head a little inclined towards it, and in this 

 attitude it remains until the insect moves, when, by 

 a stroke like lightning, the tongue is thrown forward 

 upon the victim which is instantly drawn into the 

 mouth. This tongue is very soft and fleshy almost 

 throughout, and has its base at the entrance of the 

 mouth in the concavity of the interior edge of the 

 anterior part of the lower jaw. The tongue when at 

 rest and when the mouth is shut has its free ex- 

 tremity in the back part of the mouth, the tip pointing 

 down the throat, but when the toad puts it forth it is 

 considerably elongated, the under surface of the tip 

 being embued with a viscid mucous secretion, the 

 insect is secured by its adhesive quality. When the 

 prey is taken it is slightly pressed by the margins of 

 the jaw, but as this seldom kills it, unless it be a soft 

 tender larva, it is generally swallowed alive. 



Like the other amphibia and the reptilia generally, 

 the toad sheds its skin at certain intervals, the old 

 cuticle coming off and leaving a new one which has 

 been formed underneath in its stead. Mr. Bell 

 having often found amongst several toads which he 

 was keeping some of brighter colours than usual, 

 and with the surface moist and very smooth, had 

 supposed that this appearance might have depended 

 on the state of the animal's health, or the influence 

 of some peculiarity in one or other of its functions. 

 On watching carefully, however, he one day observed 



a large one, the skin of which was particularly dry 

 and dull in its colours, with a bright streak down the 

 mesial line of the back, and on examining further he 

 found a corresponding line along the belly. This proved 

 to arise from an entire slit in the old cuticle which 

 exposed to view the new and brighter skin under- 

 neath. He soon observed that the two halves of the 

 skin thus completely divided continued to recede 

 further and further down from the centre, and became 

 folded and rugose, and after a short space by means 

 of the continual twitching of the animal's body it was 

 brought down in folds on the sides. The hinder leg, 

 first on one side and then on the other, was brought 

 forward under the arm which was pressed down upon 

 it, and on the hinder limb being withdrawn, its 

 cuticle was left inverted under the arm, and that of 

 the anterior extremity was then loosened and at 

 length drawn off by the assistance of the mouth. 

 The whole cuticle was thus detached and was then 

 pushed by the two hands into the mouth in a little 

 ball, and swallowed at a single gulp. Mr. Bell says 

 that he afterwards had repeated opportunities of 

 watching this curious process, which did not 

 materially vary in any instance. 



And now we will examine the toad internally. 

 There is a maxim that the more carnivorous an 

 animal is, the shorter and the less flexuous is its 

 intestinal canal, a fact which is well illustrated by 

 the toad, and in fact by the suborder to which the 

 toad belongs. For whereas in the tadpole, which is 

 herbivorous, we found this canal so many times the 

 length of the creature's body, here in the grown toad 

 we find the canal about once and a-half the length 

 of the whole body. 



The toad's liver generally consists of three lobes, 

 but sometimes of two only. A fatty matter, in shape 

 something like two four-fingered hands, and generally 

 of a yellowish colour, is deposited or secreted in the 

 toad, its use is supposed to be a provision for the 

 support of the animal during its torpid hybernation 

 in the cold months. 



I think that I have been fortunate enough to see 

 the action of the toad's heart, though I should think 

 that the action I saw was very imperfect. As I was dis- 

 secting a toad, and had its stomach open before me, I 

 fancied I saw (and it rather startled me, I confess) its 

 heart move, so I watched and in a short time the heart 

 appeared to be convulsed, shrank up, turned pale, 

 and then expanding, resumed its red colour ; this it 

 did several times at intervals of about twenty seconds. 



The respiration of the toad is both pulmonary, i.e. 

 by means of lungs, and cutaneous, i.e. by means of 

 the skin. The former function, that of breathing 

 by lungs, is effected not by successive alternations 

 of contraction and dilatation — a movement which, 

 as the toad possesses no ribs, or at least but rudi- 

 mentary ribs, is impossible — but by the act of swal- 

 lowing air, the deglutition of air. The air is inhaled 

 through the nostrils by the dilatation of the pharynx, 



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