EARTHWORMS 163 



own elasticity, and the structure is left in the ground as a lemon- 

 shaped cocoon containing about six eggs. The cocoons are about 

 i inch or less in length, and each as a rule produces but one 

 young worm, the remainder of the contained eggs perishing. The 

 presence of the thickened band, which is known as the " cingulum " 

 or " clitellum " (" saddle " would form an appro- 

 priate and intelligible English equivalent) is 

 therefore an indication that the worm has reached 

 maturity. All earthworms are hermaphrodite, 

 that is to say, they possess both male and 

 female organs. The male openings are situated ^ 



on the right and left sides where these pass into FlG - 6a Cocoons 



....,,,, , of earthworm. 



the under side in the I5th segment, and can A, full ;B, empty. 



easily be recognised by the presence of thickened 



lips surrounding the actual holes. The female openings through 



which the eggs pass out of the body are in the corresponding 



places in the I4th segment, but are generally very difficult to 



detect. 



Colour. The colour of most of the commoner species of worms 

 is more or less pinkish or purplish red. As in our own bodies so 

 here the colour is not that of the skin itself, but of the blood 

 which shows through the skin. It is an interesting fact that the 

 red colouring matter is identical in character with our own, and 

 has the same duty to perform, namely, to seize the oxygen of the air 

 and to carry it to all parts of the body. In ourselves, of course, 

 the oxygen is obtained as the blood courses through the lungs, 

 whereas in the worm there is no special organ for breathing, but 

 the oxygen of the outer air is absorbed direct through the skin. 

 To render this possible the skin itself is extremely thin, and is 

 kept constantly moist by its own slime; there is further, in 

 every segment, a special set of blood vessels which pass very close 

 under the skin so as to bring the blood as near to the surface as 

 possible. These blood vessels start from the main blood vessel, 

 which is visible through the skin as a dark red line up the middle 

 of the back. 



In addition to the prevailing red colour there is a beautiful 

 play of " rainbow " colours all over the surface of the body. 

 This iridescence is not due to any actual pigment, but to 



