INTELLIGENCE, ETC., IN LOWER ANIMALS 69 



ways in which a squirrel, a field-mouse, and a nuthatch 

 extract the kernels of hazel-nuts. 



The many amateurs of the eighteenth century natu- 

 rally demanded books written to suit them, and 

 illustrated books with coloured plates, coming out in 

 parts, found a ready sale. Some were devoted to 

 insects, others to microscopic objects. In accordance 

 with prevalent belief, the writers made a point of 

 tracing the hand of Providence in the minutest organ- 

 isms ; many popular treatises were altogether devoted 

 to natural theology. Some few of these natural history 

 miscellanies contained original work, which has not yet 

 lost its interest. The best is Roesel's Insecten-belusti- 

 gungen (four vols. 4to., 1746-61), memorable among 

 other things for containing the original description of 

 Amoeba. For English readers Henry Baker wrote The 

 Microscope Made Easy (1743) and Employment for the 

 Microscope (1753)' 



Intelligence and Instinct in the Lower Animals. 



The period with which we are now concerned (1741- 

 1789) initiated the profitable discussion of the mental 

 powers of animals. We are unable for lack of space 

 to follow the investigation from period to period, and 

 must condense into one short section whatever its 

 history suggests. 



In the year 1660 Aristotelians were still discoursing 

 about the vegetative and sensitive souls which bridged 

 the gulf between inanimate matter and the thinking 

 man. Descartes had tried to prove that the bodies 

 of men and animals are machines actuated by springs 

 like watches. Man, however, according to Descartes, 

 possesses a soul wholly different in its properties from 

 his body, and apparently incapable of being acted upon 



