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The Animal World in a Handful of Algae. 



By Frank Collins Baker Curator, Museum of Natural History, Uni- 

 versity of Illinois, Urbana, Illinois. 



WHEN the warm spring days 

 come and the ice leaves the 

 ponds and streams and the 

 air becomes vibrant with the vernal 

 resurrection of life, our thoughts turn 

 to the great world which has lain bur- 



THE GAMMARUS IS VERY INTERESTING. 



ied beneath ice and snow for so many 

 months. We long to sally forth with 

 collecting apparatus and gather the 

 familiar forms of life that captivated us 

 ere winter set his seal upon the earth 

 and turned it brown and desolate. 



Of the great out of doors no part 

 quite equals the ponds, streams, and 

 ditches for interest. It has been said 



THE HYALELLA MAKES ONE LAUGH. 



by an eminent American biologist that 

 a body of water, as a pond or lake, is 

 a microcosm which is isolated in great 

 part from the rest of the world and in 

 which the great forces of Nature are 

 working 1 out the evolution of the crea- 



tures that inhabit it. The life of the 

 terrestrial world might be suddenly 

 brought to an end without greatly af- 

 fecting the life of this small world. 

 Such a microcosm is inhabited by a 

 host of animals of various sizes and 

 variety, though mostly minute, which in 

 the aggregate represent all of the high- 

 er groups of the animal kingdom. Here 

 are the hunters and the hunted, the 

 former practising every art and trick 

 known to predaceous animals for ob- 

 taining their prey. The great majority 

 of the inhabitants of this small world, 

 however, are vegetarians feeding upon 



THE ASSELLUS MAKES A COMMOTION. 



the plants which thrive abundantly in 

 such a habitat. 



Without plant life, animal life would 

 be impossible. As we observe a body 

 of fresh water filled with weeds, pond 

 scums, filamentous algae, and higher 

 plants we are led to wonder if this mass 

 of living substance is of any value. If 

 we examine some of this material we 

 will find it filled with many small ani- 

 mals whose bodies are the same color 

 as the plant ; and it is at once realized 

 that these small animals are eating the 

 algae and by so doing are converting- 

 it into animal food which the carni- 



