Marsh. 219 



How do tadpoles originate ? As I have said before, from 

 eggs. That large toad with its mouth out of water is a 

 female ; at least, so one would imagine from its large size. 

 The male is smaller, and of a much more slender build. 

 Draw your stick along the edge of the pool ! Ah ! You are 

 bringing up long double jelly-like strings on your stick. 

 These strings are composed of the eggs of the toad, each 

 of which has a black nucleus in the centre. They prove a 

 considerable trouble to pull out of the water, and continually 

 break, because they are fastened round the stems and roots 

 of the plants growing in the pool. 



You have got them out at last ! Now observe the tiny 

 black yelks. These black specks will soon enlarge and 

 become subdivided into a number of minute cells, which 

 absorb and live on the jelly-like mass which surrounds them, 

 and in about three weeks the tadpoles, with their large 

 heads and tails, will emerge ; they are rather smaller and 

 much darker than the tadpoles of the frog, although, in other 

 respects, very similar to them. This is a very late batch of 

 eggs. They are usually laid in April and early May. In 

 June the toads commence to betake themselves to dry land 

 again, and travel long distances from the pools to fields and 

 gardens, where they revel by night, feeding on beetles, slugs, 

 worms and caterpillars. Probably this is one of the best 

 friends the gardener has, but he does not always appear to 

 think so. 



The mechanical processes by means of which the breathing 

 of adult frogs and toads is effected is very remarkable. We 

 have seen that in the tadpole state they breathe by means 

 of gills, in the adult state by means of lungs. In mammals, 

 the presence of a muscular diaphragm and of ribs moved by 



