INSECTS IN GENERAL. 37 



bute the nutritious fluids which it contains, into all parts of 

 the body. It must, also, by the aid of certain instruments, 

 for the purpose of denoting the qualities of bodies, attract 

 or repel, approach or avoid, certain substances. How the 

 generative functions have been modified by the organs of 

 motion and sensation, it is only necessary to allude to. 



The consequences of these truths, properly followed up, 

 will assist us in developing the elements of the natural classi- 

 fication of animals. Havina; once established that the exis- 

 tence of the organs of motion and sensation is the charac- 

 teristic distinction of animals, it is certain, that the more that 

 these faculties are developed in animals, the more are the 

 latter removed froin vegetables, and vice versa. 



The degree of this development is easily observed. If 

 we find animals endowed with the faculty of reproducing 

 themselves by germs or slips, of being dried up, and preserv- 

 ing the characters of life through the influence of moisture, 

 light, or other natural agents ; being able to exist only in 

 a liquid medium ; often fixed upon a point of space in the 

 very midst of their aliment, which many of them absorb 

 through external pores ; shewing but few vestiges of any 

 thing like motion — such animals assuredly exhibit the nearest 

 possible relation to plants. They have neither distinct 

 nerves, nor organs of sense, with the exception of passive 

 feeling; no alimentary or digestive tube, no articulated 

 appendages for motion, no distinct organs of respiration. 

 These are the zoophytes, the last class of animated nature. 



We next find animals condemned for the most part to live 

 in water, whose motions are slow, and often hardly percep- 

 tible. They are, therefore, destitute of several of the organs, 

 of sense, though possessing nerves. They have no articulated 

 limbs. Their mode of generation sometimes resembles that 

 of plants. Sometimes there is a triple complication of dis- 

 tinct individual sex ; sometimes the sexes are united in one 

 and the same being — such are the molhisca. 



