3 



THE PRINCIPLES 



BIOLOGY. 



HEEBEET SPENCEE, 



AUTHOR OF "SOCIAL STATICS," "THE PRINCIPLES OF PSYCHOLOGY, 



" BttSAYB : SCIENTIFIC, POLITICAL, AND SPECULATIVE," 

 "FIRST PRINCIPLES," ETC. 



VOL. II. 



NEW YOEK: 

 D. APPLETON AND COMPANY, 



1, 3, AND 5 BOND STREET. 



1884. 



