NA TURE 



553 



HABIT AND INSTINCT. 



Habit and Instinct. By C. Lloyd Morgan, F.G.S. 

 Pp- 351- (London : Edwin Arnold, 1896.) 



THE substance of this interesting work was delivered 

 in 1896, as a course of Lowell Lectures at Boston, 

 and as lectures in other parts of the United States. 



The arrangement of the book is excellent : the first 

 chapter deals with " Preliminary Definitions and Illus- 

 trations," the second, third, and fourth with original 

 observations of the author upon the young of many 

 species of birds ; the fifth, with observations upon young 

 mammals. These four chapters form the chief material 

 upon which, in the remainder of the volume, a very 

 interesting and important discussion upon animal habits 

 and instincts is carried on, concluding, with the con- 

 sideration, in the twelfth, thirteenth, fourteenth and 

 fifteenth chapters, of the following subjects, which 

 present so many aspects of wide interest : — " The 

 Relation of Organic to Mental Evolution," "Are 

 Acquired Habits inherited?" "Modification and Varia- 

 tion," " Heredity in Man." 



In the preliminary discussion in the first chapter a 

 very beautiful example of a complex instinct is afforded 

 in the behaviour of the Yucca moth {Pronuba yuccasella). 



" The silvery, straw-coloured insects emerge from their 

 chrysalis cases just when the large, yellowish-white, bell- 

 shaped flowers of the yucca open, each for a single night. 

 From the anthers of one of these flowers the female 

 moth collects the golden pollen, and kneads the adhesive 

 material into a little pellet, which she holds beneath her 

 head by means of the greatly enlarged bristly palps. 

 Thus laden, she flies off and seeks another flower. 

 Having found one, she pierces with the sharp lancets of 

 her ovipositor the tissue of the pistil, lays her eggs 

 among the ovules, and then, darting to the top of the 

 stigma, stuffs the fertilising pollen-pellet into its funnel- 

 shaped opening." 



" Now, the visits of the moth are necessary to the 

 plant. It has been experimentally proved that, in the 

 absence of the insects, no pollen can get to the stigma 

 to fertilise the ovules, and the fertilisation of the ovules 

 is necessary to the larvae, which in four or five days are 

 hatched from the insect's eggs. It has been ascertained 

 that they feed exclusively on the developing ovules, and 

 in the absence of fertilisation the ovules would not 

 develop. Each grub consumes some twenty ovules, and 

 there may be three or four such grubs. But the ovary 

 contains some two hundred ovules. Of these, therefore, 

 say, a hundred are sacrificed to the grubs of that moth, 

 through whose, instrumentality alone the remaining 

 hundred can be fertihsed and come to maturity." 



Concerning this elaborate sequence of actions the 

 author points out that they are performed but once in 

 the lifetime of the moth, without instruction, without 

 imitation, and without the guidance which an experience 

 of the subsequent fate of the eggs might provide. The 

 essentially adaptive nature of the sequence is insisted 

 upon. 



The relation between what is " congenital " and what 

 is "acquired" is considered in some detail, and by 

 many examples, especially that of the training of falcons, 



NO. 1485, VOL. 57] 



it is shown that the limits of what can be acquired are 

 determined by what is congenital, 



" The behaviour of a trained falcon is an adaptation^ 

 and modification of the hawk's congenital instincts as a 

 bird of prey. The finished performance is part instinct 

 and part habit. The basis is instinctive and congenital %. 

 the modification is a matter of acquired habit." 



This valuable preliminary discussion of the subject- 

 matter of the volume is summed up in the following 

 statement — 



"From the biological point of view . . . instincts 

 are congenital, adaptive, and coordinated activities of 

 relative complexity, and involving the behaviour of the 

 organism as a whole. They . . . are similarly performed 

 by all like members of the same more or less restricted 

 group, under circumstances which are either of frequent 

 recurrence or are vitally essential to the continuance of 

 the race. While they are, broadly speaking, constant in 

 character, they are subject to variation analogous to that 

 found in organic structures. They are often periodic in 

 development and serial in character. They are to be 

 distinguished from habits which owe their definiteness 

 to individual acquisition and the repetition of individual 

 performance." 



The author has rendered a great service in thus bring- 

 ing together the essential characteristics of instinct as 

 opposed to habit in a few clear brief sentences. 



The interesting experiments of the author upon the 

 activities and instincts of young birds must be read in full 

 to be properly appreciated. They have a most important 

 bearing upon problems of very wide interest, such as 

 the hereditary transmission of acquired characters, the 

 theories of Protective Resemblance, Protective Mimicry, 

 Warning Coloration, &c. These experiments and ob- 

 servations should be studied carefully by all who either 

 criticise or support the abov^-mentioned theories. The 

 general results only can here be indicated. 



The observations of Douglas Spalding {Macmiltaris 

 Magazine, February 1873) upon young chickens have 

 been much quoted, but many of his conclusions are here 

 shown to be without sufficient foundation. Thus Lloyd 

 Morgan's observations do not support the conclusion- 

 that there is any instinctive recognition of the mother 

 hen by the young chick which sees or hears her for the 

 first time. He does not find the accuracy of aim is at 

 first equal to that recorded by Spalding, and he gives 

 strong reasons for the belief that the evidence of in- 

 stinctive fear of a bee or a hawk is not due to alarm at 

 these animals as such, but merely one example of the 

 extreme shyness of young birds at any unusual sight or 

 sound. 



There is no instinctive knowledge of food or water.. 

 Any object of suitable size and within the right distance is 

 struck at ; but the chicks are very quick in learning from^ 

 the experience thus gained. A young chick, two days 

 old, which had learnt to select pieces of yolk of ^g'gy 

 twice seized a piece of orange-peel of about the same 

 size and shape. After this he could not be induced to 

 touch it, and for a time refused yolk of ^%%. The con- 

 spicuous caterpillars of the cinnabar moth, alternately 

 ringed with black and yellow, were thrown to some 

 chicks, which seized but immediately dropped them and 

 wiped their bills. Later in the day the caterpillars were 

 again offered, and only tried once by some of the chicks. 



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