PLANARIA ARETHUSA. 



bled to substitute experiment. Of such 

 infinity are the ways adopted by nature for 

 the perpetuation, welfare, and conservation 

 of her creatures, that analogies in their or- 

 ganization appear unnecessary for the sub- 

 sistence of life. The rest of the planarise 

 then, aware of the presence of food, in hke 

 manner began to issue forth their long 

 slender trunks, and either insinuate them 

 into the larger portions of fish lying at the 

 bottom of the water, or absorb the particles 

 suspended upon it. 



In imitation of the name bestowed on the 

 trunk of the elephant, the extensile organ 

 serving to imbibe the nutriment of many of 

 the smaller animals, is called a proboscis, 

 whether it simply unfolds from the root, 

 protrudes from a sheath, or unwinds from a 

 regular series of volutions. But in none is 

 the designation equally strict and appro- 

 priate as in the planaria. There it is 

 absolutely the organ of the elephant in 

 miniature, with this exception that it is 

 neither annulated, nor composed of seg- 



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