S52 PRACTICAL AND SCIENTIFIC ZOOLOGY. 



manner, either with eyelike spots, or delicate stripes, so 

 that the species can be easily detected. As what we have 

 already said, on this subject is intelligible even to the 

 student, there seems no occasion to dwell further upon 

 the distinctions of Species. 



(432.) Varieties, in a state of nature, have their 

 origin from some unusual, local, or accidental cause, 

 either in their birth, their situation, or their food : they 

 do not perpetuate the peculiarities they possess ; but, 

 the causes being removed, nature returns again, as it 

 were, to her original type. Scanty food produces dwarfs, 

 so also does unusual heat or cold with insects removed 

 from that temperature most congenial to their consti- 

 tution. Varieties, generally speaking, are rare, even 

 where the species from which they vary are common. 

 As they are evanescent, so they need hardly be described, 

 except to illustrate something more than the bare fact. 



(4.'?3.) We have now laid before the young natu- 

 ralist the essence of those general principles which have 

 been more fully and more scientifically discussed in a 

 former part of this volume. He may possibly be dis- 

 posed to question the necessity of grounding himself in 

 this sort of information, but he may rest assured that 

 it will give to his more immediate pursuits, and to his 

 future progress, a degree of interest and of facility which 

 no other plan of study can produce. The more tho- 

 roughly we understand the groundwork of any depart- 

 ment of knowledge, the more rapid will be our subsequent 

 advancement in its details. These preliminary chap- 

 ters, on the principles of his science, should therefore 

 be perused until their substance is impressed upon the 

 memory; he will then be better qualified to understand, 

 and to be interested in, the more enlarged views already 

 taken of the subject : while the amateur, not desiring to 

 be profoundly versed in the philosophy of that which is 

 to him a mere recreation or amusement, may at once 

 proceed to the following chapter. 



