vi Elementary Biology. 



add that that summary is intended to be suggestive rather 

 than exhaustive. 



I have further endeavoured in the succeeding chapters 

 to keep prominently in the foreground the dependence of 

 Biology on Physics and Chemistry, and the relationship of 

 morphological and physiological details to general principles. 

 I have tried to keep constantly before me the evils of the 

 * cram ' system in education, and this must be my apology, 

 if an apology be deemed necessary, for the introduction of 

 so many speculations and explanations of causal relationship. 

 I am fully aware of the fact that many theories referred to 

 in the text are still matters of discussion, yet I am of opinion 

 that working hypotheses not only serve to weave apparently 

 isolated facts together, but give a certain vividness and in- 

 terest to what would otherwise prove too often a bare and 

 lifeless catalogue of data. 



It may seem at first sight that I have given undue pro- 

 minence to the botanical aspect of Biology. I have done 

 so intentionally, and for two reasons. First, because there 

 is no want of sound text-books both practical and theoretical 

 on Animal Biology by most competent authors, and no 

 advantage, it seemed to me, was to be gained by a repe- 

 tition of what had already been so often and so ably done ; 

 and secondly, because Plant Morphology and Physiology, 

 from their relative simplicity and clearness as compared 

 with Animal Morphology and Physiology, are more suit- 

 able for elementary study. ! 



1 A word of explanation seems necessary apropos of the terminology 

 I have adopted in describing the reproductive organs both in the plant 

 and animal kingdoms. In my experience nothing is more confusing to 

 the student than the diversity of the systems of nomenclature at present 

 in use in text-books. The time has now come for the introduction of 

 a uniform terminology in both these subsciences, and reform may not 



