12 EARTHWORMS AND LEECHES [CH. I 



carmine, or iron injected into the body are also excreted 

 by the activity of the chloragogen cells (Kowalevsky 1 , 

 Schneider 2 ). In worms which have been starved and in 

 which, presumably, there is a deficiency of waste products 

 these cells are pale and dull in colour. 



The amoeboid corpuscles of the coelomic fluid have a 

 remarkable power of attacking bacteria and other micro- 

 scopic organisms such as Gregarines and Infusorians or 

 even small Nematode worms. If such parasites enter the 

 ccelom the amoeboid cells surround and destroy them. 

 Their operations are however not confined to the inside 

 of the earthworm. The slime of the body surface is in part 

 composed of mucus secreted by the skin, and in part of 

 coelomic fluid and its corpuscles which find exit through 

 the dorsal pores. The corpuscles are thus able to -attack 

 and destroy bacteria before they effect an entry into the 

 body. There is no doubt that a worm is constantly 

 exposed to these minute organisms for the upper layers of 

 the soil teem with them. The slime itself is a protection, 

 for it both arrests -the bacteria and holds them stranded in 

 the trail which the worm leaves behind it in its progress. 

 The application of a grain of some irritant, such as 

 corrosive sublimate, enables one to see how a worm 

 protects itself. Immediately the irritant touches the skin 

 the segments in front and behind the seat of injury are 

 forcibly constricted while the affected segment itself swells 

 up in consequence of the increased pressure brought to 

 bear upon it from both sides. At the same time there is 



1 BioL Centralbl. ix. 1890. 2 Zeit. wiss. Zool. LXI. 1895-6. 



