CHAPTER XIII 

 WHEEL ANIMALCULES 



TWQ hundred years ago the Dutch naturalist 

 Leuwenhoek, who made many discoveries with the 

 highly magnifying lenses which he himself ground 

 and mounted, wrote to the Royal Society of London 

 that he had " discovered several animalcula that protrude 

 two wheels out of the forepart of their body as they 

 swim, or go on the sides of the glass jar in which they 

 are living." He says that "the two wheels are thick 

 set with teeth as the wheel of a watch," and he sent to 

 the society for publication drawings of these wonderful 

 little creatures. This was the first account of the Wheel 

 Animalcules. Since then they have been studied by many 

 microscopists, especially by Ehrenberg, who figured many 

 in his great book on animalcules in 1838. Fourteen years 

 later the delightful English naturalist, P. H. Gosse, who 

 studied and illustrated the "sea-anemones" so ably — 

 and, by his example and charming descriptions, made 

 the keeping of these beautiful things in marine aquaria 

 a favourite occupation among people of leisure, blessed 

 with a "curiosity concerning the things of nature" — 

 published some microscopical studies on Wheel Animal- 

 cules, and continued throughout his life to make them 

 a special subject of his investigation. 



The microscope was greatly improved — in fact, reached 

 its present state of perfection — during Mr. Gosse's lifetime, 

 and a wonderful amount was added to our knowledge 



