366 The Study of Animal Life APF. 



inquiry into such matters, the most convenient introduction will 

 be found in The Evolution of Sex (Contemporary Science Series, 

 Lond., 1889), by Prof. Geddes and myself. In that work there 

 are references to others. A survey of modern opinions and con- 

 clusions in regard to heredity may be obtained from the article in 

 Chambers's Encyclopedia, whence the student will pass unbiassed 

 to the essays of Weismann, Papers on Heredity and Kindred 

 Subjects (translated by E. B. Poulton, S. Schonland, and A. E. 

 Shipley, Oxford, 1889), to the works of Francis Gal ton, especially 

 his Natural Inheritance (Lond., 1889), and to other important 

 books mentioned in the article referred to. 



Animal Intelligence. A recent work by Professor C. Lloyd 

 Morgan, Animal Life and Intelligence (Lond., 1890), supplies the 

 best introduction to those interesting questions in the discussion of 

 which the biologist becomes a psychologist. The most reliable 

 treasury of facts is certainly G. J. Romanes's Animal Intelligence 

 (Internat. Sci. Series, 4th ed., Lond., 1886), to which may 

 be added Couch's Illustrations of Instinct (1847), Lander Lindsay's 

 Mind in Animals (1879), Biichner's A us dem Geistesleben der Thiere 

 (2nd ed., Berlin, 1877) and Liebe und Liebesleben in der Thierwelt 

 (Berlin, 1879) ; Max Perty, Ueberdas Seelenleben der Thiere (Leipzig, 



1876) ; Houzeau, Des Facultes mentales des Animaux (Brussels, 

 1872). Of t unique value is the work of A. Espinas, Des Societes 

 Animates, Etude de Psychologie comparee (Paris, 1877). See also 

 P. Girod, Les Societes chez les animaux (Paris, 1890). I should 

 also mention that Brehm's Thierleben (1863-69), a great work now 

 in process of re-edition (10 vols., Leipzig), is a marvellous 

 treasury of information in regard to the ways and wisdom of 

 animals, and that we have in Verworn's Psycho- Physiologische 

 Protisten Studien (Jena, 1889) a very interesting and important 

 study of the dawn of an inner life in the simplest animals or 

 Protozoa. Of the ingenious work of animals, an admirably terse 

 description is given in F. Houssay's Les Industries des Animaux 

 (Paris, 1889). For theories of instinct, see especially Romanes, 

 Mental Evolution in Animals (Lond., 1883); Darwin, Origin of 

 Species ; Wallace, Contributions to the Theory of Natural Selection ; 

 Spencer, Principles of Psychology and Principles of Biology ; G. H. 

 Lewes, Problems of Life and Mind (Lond., 1874-79); Samuel 

 Butler, Life and Habit (Lond., 1878); J. J. Murphy, Habit and 

 Intelligence; E. von Hartmann, Das Unbewusste vom Stand- 

 punkte der Physiologie und Descendenztheorie (2nd ed., Berlin, 



1877) f' "Schneider, Der Thierische Wille (Leipzig, 1880); Eimer, 

 Organic Evolution ; Weismann, Papers on Heredity. 



The Fact of Organic Evolution. The student's first task 



in regard to Evolution is to make himself acquainted with the 



