AQUATIC WORMS 75 



cane of the leech needs little description ; it is a typical worm- 

 like animal, except that its body, which is convex, has the 

 under side flattened. 



The horse-leech, similarly to the medical, is a blood- 

 sucker, attacking tadpoles, frogs, worms, and other soft-bodied 

 creatures. 



Leeches are able to secrete slime and thus escape from their 

 enemies. Even the most carnivorous water-beetle, unless 

 starvation be imminent, leaves the leech severely alone. Al- 

 though the Hirudinia are hermaphrodites (both sexes in one), 

 yet self-fertilisation never takes place. The horse-leech lays 

 her eggs in a case made of saliva, and leaves them to hatch. 



Members of the family Clepsine behave differently ; in this 

 species the eggs are not left to their fate, but are carried 

 with the mother until they hatch ; the young then fasten 

 themselves to the under side of their parent and thus accom- 

 pany her on her travels. In case of violent accident the 

 young Clepsines may be dispersed ; should this occur, having 

 lost their parent, they loop along in a perfectly up-to-date 

 manner; but are, nevertheless, only too willing to regain 

 their former position at the first opportunity. 



The parent's maternal feelings are certainly most acute, for, 

 on meeting one of her offspring, she will twist the anterior 

 portion of her body round it, probably in order to facilitate 

 its regaining its former domicile. It is a most fascinating 

 picture to see a female Clepsine carrying her family, the 

 youngsters undulating from their maternal home, the mother 

 showing every sign of careful movement, so as not to dislodge 

 or injure those dependent on her. In fact many a human 

 mother might take a lesson from Clepsine and her large 

 family, for in her case no single heir enters the world, but 

 eight to ten sturdy miniature Clepsines arrive to be looked 

 after ; and instinct or no instinct, whatever it may be, tells 

 the mother that when she loops she must be careful, and even 

 when she undulates caution is required. 



Clepsine is said to have a partiality for snails, in fact to 

 suck these unfortunate molluscs. To our minds this seems a 

 very nasty habit. Fortunately Clepsine has not seen an 

 oyster-swallower ! 



There are several more species of British leeches, some very 

 worm-like and some very small. They all live happily in the 

 aquarium, thriving to all appearance on nothing, loving to 

 wander over the glass, which, owing to their transparency, 

 allows an easy examination of their internal organs. 



The first Wheel Animalcule or Rotifer was discovered in 



