POND LIFE. 251 



when they are in the act of contracting. This is really a series 

 of little radiating tubes, such that when the vacuoles contract, 

 the fluid which is inside them is forced out and carried 

 along the tubes all through the creature's body. And this appears 

 to be quite analogous to what is called a " circulation " in the 

 higher animals ; the little vacuole is, in fact, a heart, and the 

 minute radiating tubes are blood-vessels. 



There is still another point to be noticed in the Faramcechcm, 

 and that is, that the chlorophyll granules and certain other dark- 

 grey granules are continually moving round inside the creature's 

 body. It seems as though the semi-fluid substance of the body 

 were always moving round and round, and always in one direction, 

 the two vacuoles of course remaining still. As I said, the animal 

 swims actively about in the water searching for food, and any little 

 things that come against it are carried by the cilia to the funnel 

 leading into the body substance. You can watch the fate of those 

 Diatoms, becoming dissolved in the protoplasm, after which their 

 indigestible shells are cast out through the same funnel by which 

 they entered. 



It has been noticed that this animal propagates itself by 

 dividing down the middle, as do so many of these creatures, but 

 in the autumn large numbers of these slipper-animalcules congre- 

 gate in the bottoms of ponds or aquariums. Two unite, and their 

 contents fuse together, and the nucleus and nucleolus unite with 

 each other ; the nucleus of the one with the nucleolus of the 

 other, and vice versa. The one nucleus then becomes absorbed 

 in the other, which then undergoes division, and after five or six 

 days the whole protoplasm contained in the bodies of the two 

 animalcules will have broken up into a number of little bodies, 

 which make their escape, and singularly enough these germs are 

 sucker-bearing animals — Acinetce — such as we saw before sucking 

 their nourishment from other organisms ; and, perhaps, what is 

 more singular still, they remain sticking to their parents and 

 extracting their juice for nourishment, and this they do until they 

 are of an age to capture food for themselves, when they detach 

 themselves, and afterwards develop into complete slipper-animal- 

 cules, like their predecessors. 



And with this very brief notice of the Infusoria our lecture 

 to-night must conclude. 



