4 GENERAL HISTORY OF 



steer their course with unerring rectitude. Many of the 

 Infusoria do not possess this organ. But, mark the 

 all-wise dispensation of Providence in this respect ! — those 

 which have it live, for the most part, near the surface of 

 the water, whilst those which have it not, as the Bacillaria, 

 locate near the bottom. This circumstance in their 

 economy has not hitherto been noticed. 



Lastly, — still restricting our observations to the drawings 

 of the first plate, look at the graceful forms of the small 

 family Closterina {fig. G3 to grovp 67), which have long 

 rivetted the attention of the most eminent naturalists 

 of modern times, and which have hitherto defied all their 

 powers of investigation, aided by all the refined and 

 searching means which human ingenuity can supply, to 

 determine whether they are animals or plants ! No cha- 

 racteristic, at present known, has been found sufficient to 

 satisfy both the zoologist and botanist. 



In short, there is not one species, out of the seven 

 hundred and thirty-two described in the second part of 

 this work, but offers ample scope for the exercise of our 

 deepest reflection, at the same time that it affords an 

 admirable proof of the adaptation and design of Creative 

 Wisdom. 



For the convenience of reference, it is proposed to 

 divide this part into sections ; and, although the subjects 

 treated of may not, as respects some few of them, have 

 received all that careful investigation which they deserve, 

 yet it is presumed that sufficient has been done to lead 

 the minds of the more curious inquirer to a further 

 research. Previous to which, I present the reader with 

 Dr. Ehrenberg's summary of the subject : — 



