AQUATIC WORMS 71 



resembling a minute drop of black sealing-wax, but when on 

 the move they elongate and glide slowly and gracefully. Their 

 black eyes, so characteristically cruel, are protected between 

 two thin membranes, so that the creature is probably able to 

 see both above and beneath it at the same time. Similarly to 

 the Rhabdocoelida, the Planarians are carnivorous, feeding 

 upon both living and dead insects, molluscs, &c. Their skin is 

 furnished with rods, some resembling needles, whilst others are 

 hook-shaped. These constitute the Planarian's protective 

 weapons, and are fired out in case of emergency. These darts, 

 although only visible under high-power lenses, are certainly 

 formidable weapons to the various micro-pond inhabitants. 



The mouth is not on the head, as one might expect, but is 

 situated on the underside of the body, towards the centre of 

 the creature, so that we might roughly say that an opening in 

 the abdomen "acts as a mouth." Therefore, when eating, the 

 Planarian must cover its victim. The animal certainly does 

 not bolt its food, but eats slowly, taking several hours to finish 

 a meal. On one occasion the writer placed a small may-fly 

 larva near to a Planarian. The latter rose up in a very 

 peculiar manner and curled up the sides of its head, and then 

 advanced slowly towards its victim and covered it. After an 

 hour the Planarian glided away, leaving nothing but the skin 

 of the unfortunate insect. On another occasion a dead snail 

 was placed in a saucer containing two Planarians ; one of these 

 creatures, as if scenting the snail, lifted itself, and slowly 

 turned back the edges of its head. It then glided towards the 

 snail, and was on the point of touching it when, as if changing 

 its mind, it rose and passed to the left. The very next moment 

 the Planarian again turned and came towards its prey, rubbing 

 up against it (simulating a purring cat), rubbing and twisting 

 as if it enjoyed the sensation, occasionally allowing one side of 

 its body to glide over the obstacle and then the other. After 

 behaving in this manner for a considerable time, the Planarian 

 wandered away. The next day the snail was no longer there, 

 and it can only be concluded on circumstantial evidence that 

 it had been eaten, although neither of the Planarians showed 

 any signs of a heavy meal. 



On one occasion two Planarians were seemingly at logger- 

 heads. They raised themselves on the posterior end of their 

 bodies and, entwined about each other, were swaying to and 

 fro. On being separated the cause of the trouble was revealed 

 in the personage of a small worm, well covered with some sticky 

 slime-like substance (probably digestive juices). 



Planarians multiply both sexually and asexually. In the latter 



