20 POND LIFE 



other speck of organic matter. Gradually the sides of the 

 amoeba elongate until the prey is literally engulfed, the Desmid 

 being deposited in the centre of a lump of protoplasm. When 

 the victim has been digested, the amoeba opens and wanders 

 away, leaving the remains of its meal behind it. 



A time comes when the amoeba, having lived a happy life, 

 becomes fat, and then the single-celled creature forms a waist, 

 which becomes more fashionable until, having reached a mini- 

 mum, it breaks, and two amoebas crawl in different directions. 



The amoeba reacts to certain stimuli ; electric currents, &c., 

 show various effects. 



It is most active in temperatures of about 100 F., and may be 

 killed by poisons or excessive heating. 



The famous Leucocyte or Phagocyte (white blood corpuscle), 

 which inhabits the veins and arteries of the higher animals, is 

 similar to the amoeba, wandering along when emergency calls, 

 by means of " temporary feet." The amoeba may be found 

 inhabiting the mud at the bottom of the pond, and can usually 

 be easily discovered under a fairly low-power lens. 



Under adverse conditions, such as when the pond dries up 

 during a drought, the amoeba forms a case or cyst, and thus 

 encysted remains dormant until conditions are again favour- 

 able. It may happen that the encysted amoeba is carried by 

 the wind to another pond. Thus micro-life appears in fresh 

 situations. 



Certain of the Infusoria have cilia, and are known as Ciliata. 



Stylonychia mytilus is a comparatively large protozoon, and 

 will be seen swimming about in a most characteristic manner. 

 It is a broadly oval organism with cilia along its sides. The 

 mouth is very large, and the cilia with which it is furnished 

 are most energetically waved, proving that at all events 

 Stylonychia has an appreciable appetite. 



This little creature, like many others, deserves that its name 

 should be inscribed upon marble, as an example of energy, for 

 the animalcule seems to be well stored with this quality, and 

 free from any signs of fatigue. It is continually darting to 

 and fro, as if the forward or backward movement resulted in 

 the stretching of an elastic band, which suddenly becoming taut 

 drew the creature back, whether it wished to come or not. 

 Sometimes it crawls, at other times it travels by leaps and 

 bounds, but usually the dart-like movement is its mode of 

 progression. 



It is most interesting to study Stylonychia, although it needs 

 much patience, as it continually leaves the field of focus at the 

 critical moment. 



