CHAPTER VIII. 



HOMOLOGIES. 



Animals made-up of parts mutually related in various ways. — "What homo- 

 logy is. — Its various kinds, — Serial homology. — Lateral homology. — 

 Vertical homology. — Mr. Herbert Spencer's explanations. — An internal 

 power necessary, as shown by facts of comparative anatomy. — Of ter- 

 atology. — M. St. Hilaire. — Professor Burt Wilder. — Foot-wings. — Facts 

 of pathology. — ]\Ir. James Paget. — Dr. William Budd. — The existence 

 of such an internal power of individual development diminishes the 

 improbability of an analogous law of specific origination. 



That concrete wliole wliicli is spoken of as "an individual " 

 (such, e.g., as a bird or a lobster) is formed of a more or 

 less complex aggregation of parts which are actually (from 

 whatever cause or causes) grouped togetlier in a harmonious 

 interdependency, and which have a multitude of complex 

 relations amonq-st themselves. 



The mind detects a certain number of these relations as 

 it contemplates the various component parts of an indi- 

 vidual in one or other direction — as it follows up different 

 lines of thought. These perceived relations, though sub- 

 jective, as relations, have nevertheless an objective founda- 

 tion as real parts, or conditions of parts, of real wlioles ; 

 they are, therefore, true relations, such, e.g., as those 

 between the riulit and left liand, between the hand and 

 the foot, &c. 



