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G. T. LADD, ELEMENTS OF PHYSIOLOGICAL PSYCHOLOGY. 587 In places there is confusion amounting almost to contradiction. For example, Prof. Ladd says, and correctly (p. 455) : " Objects of sense [i.e., perceptions] are in no case exact copies of ready- made things which exist extra-mentally just as they are afterwards per- ceived, and which get themselves copied off in the mind by making so- called impressions upon it ; they are mental constructions ". * But it had previously been said (p. 391) : " It is position and extension in space which constitute the very pecu- liarity of the objects as no longer mere sensations or affections of the mind. As sensations they are neither out of ourselves nor possessed of the qualities indicated by the word spread-out. As objects of sense [i.e., perceptions] they are both out and ' spread-out V Chapter viii. gives a tolerably complete summary of experi- ments which have been made on the " Time-relations of Mental Phenomena". Prof. Ladd does not often venture to criticise, and in several cases praises work of doubtful value. It is said (p. 497), and very truly, "Experimental research does not ex- plain the origin or nature of our idea of time and its relations ' ' . Eesearch in the field of psychometry has, however, been tolerably successful, and has yielded results not without importance. It is interesting simply to know that the time it takes to perceive, to will, to remember, &c., can be determined, and that this time is constant for the same individual and under the same circum- stances, but is a function of race, age, occupation, &c. The fact that changes in the brain and changes in consciousness correspond in time throws light on the relations between the two. Further, psychometric research helps us in analysing perceptions and in studying attention, volition, &c. Chapter ix., on " Feelings and Motions" [Movement? Emo- tion?], was evidently written with extensive knowledge of the German and English literature concerned with the subject. It is, however, a pity that use could not have been made of Mr. Ward's important article in the Encyclopaedia Britannica, with its clear definitions and treatment of feeling, attention, &c. Prof. Ladd says (p. 344) : " Sensations of motion, of innervation and weariness of the muscles, the so-called 'common sensations' (or sensations of the sensus communis), the sensations of pain or pleasure and those delicate shadings of sensations, as it were, which constitute the ' local colouring ' of all the feelings to which we assign a definite place in the fields of sight and touch, are all closely allied to sensations of pressure and temperature ". Prof. Ladd also speaks of " feeling with its colour-tone of pain or pleasure" and of an "involuntary act of will". Yet, in spite of considerable confusion, the chapter is not wanting in interest and value. The "feeling of effort" is treated in this chapter ap- parently owing to an ambiguous use of the word "feeling". In the battle now waging over the sense of effort, Prof. Ladd sides