i64 NATURAL SCIENCE. March, 



antecedent to experience, our author summarises some of the conclu- 

 sions to be drawn from the observations as follows : — 



" I. That which is congenitally definite as instinctive behaviour 

 is essentially a motor response or train of motor responses. Mr. 

 Herbert Spencer's description of instinct as compound reflex action is 

 thus justified. 



" 2. These often show very accurate and nicely-adjusted con- 

 genital or hereditary co-ordinations. 



" 3. They are evoked by stimuli, the general type of which is 

 fairly definite, and may, in some cases, be in response to particular 

 objects. Of the latter possibility we have, however, but little satis- 

 factory evidence. 



" 4. There does not seem to be any convincing evidence of 

 inherited ideas or knowledge (as the term is popularly used) ; that is 

 to say, the facts can be equally well explained on the view that what 

 is inherited is of the nature of an organic response. 



" 5. Association of ideas is strong, and is rapidly formed as the 

 result of individual acquisition. 



" 6. Acquired definiteness is built, through association, on the 

 foundation of congenital responses, which are modified, under 

 experience, to meet new circumstances. 



" 7. Acquired definiteness may pass, through frequent repetition, 

 into more or less stereotyped habit." 



Having thus given the author's standpoint and his main con- 

 clusions from a body of well-observed facts, we will pass on to his 

 treatment of those activities of adult animals which are generally 

 classed as instinctive. 



In the chapter on " Some Habits and Instincts of the Pairing 

 Season," the songs, dances, and displays of plumage by birds are 

 described, and Professor Lloyd Morgan seems inclined to the con- 

 clusion that their great development indicates the action of that form 

 of sexual selection termed " preferential mating." Some additional 

 observations are quoted which support this view, but the final con- 

 clusion is that — " in all these matters further and fuller evidence from 

 direct observation is to be desired." 



The next chapter is on " Nest-building, Incubation, and Migra- 

 tion," and affords much matter for careful consideration. As to nest- 

 building, I have always urged that careful experiments are required 

 before we can accept as instinctive the building of a peculiar type of 

 nest by each species of bird ; and we find a few such recent experi- 

 ments now adduced. But when we remember how such a careful 

 experimenter as Spalding was led to wrong conclusions through not 

 varying his experiments sufficiently, the few experiments yet made on 

 nest-building under conditions by no means rigid and with results not 

 described in sufficient detail, can hardly be accepted as settling the 

 question. This is one of the problems that can only be finally settled 

 by experiments tried on a large scale and with every precaution, and 

 the results preserved for comparison and study ; and if ever an 

 experimental biological farm is established this subject of nidification 



