276 



DISCOVERY 



III the concluding chapter the author deals briefly 

 with the question of the relation of the flowering plants 

 to the older Cycadean types knowTi as the Bennettitales ; 

 he fa\-ours an affinity between these two groups, ^^'hile 

 it would be rash to deny the possibility of any real 

 relationship, the opinion may be expressed that no 

 evidence has so far been presented which enables us to 

 understand the evolution of the flower. The tendency 

 to connect group with group is now much less apparent 

 than formerty. . Evolution has operated along many 

 different lines, and it is not improbable that the history 

 of the now dominant flowering plants has had but little 

 connection with that of the group which to a large e.xtent 

 occupied the corresponding position in the later Triassic, 

 the Jurassic, and early Cretaceous periods. 



A. C. Seward. 



A NEW IXTERPRETATION OF DREAMS 

 Conflict and Dream. By W. H. R. Rivers, Lit.D., 

 F.R.S., etc. (Kegan Paul, lis. bd.) 



AVhen Professor Freud first enunciated his psychology 

 of dreams, he laid down certain ^■ery definite principles 

 which were claimed to be applicable without exception 

 to all dreams, whether of children or of adults, of normal 

 or of neuropathic individuals : but to many of the workers 

 who entered the new field that liad been opened up it 

 seemed, as more varied psychological data were obtained, 

 that the original " pioneer " theories were too rigid, 

 and \-arious attempts were made to expand them. Freud 

 himself, largely as a result of a study of the war neuroses, 

 made several important modifications in his theories, 

 and these were recently published in his monograph. 

 Psycho-analysis and the Psychology of the Ego. 



The late Dr. Rivers, working upon his own dreams 

 and those of patients suffering from war neuroses, came 

 to the conclusion that all dreams could not be explained 

 as the symbclic fulfilment of a repressed wish (as Freud 

 had originally claimed), but might express any emotional 

 state and might be regarded in general as an attempted 

 solution of a conflict, either conscious or unconscious. 



Dr. Rivers totally rejects Freud's theory that the form 

 of the dream is determined by a psvchological process 

 (the " censorship ") which allows the disturbing thoughts 

 which would wake the sleeper to appear only in the 

 disguised and undisturbing form of the dream, and, 

 instead, he holds that the form of the dream is to be 

 explained solely by the fact that in sleep we revert to a 

 more primitive rncde of thought, of which the dream is 

 the natural and dramatic expression. The conception 

 of regression during sleep, which was originally emphasised 

 by Freud, is expanded by Dr. Rivers into the attractive 

 theory that the more deeply we sleep the farther we 

 recede from our waking and familiar self and the more 

 primitive and distorted become our dreams. This theory 

 is the coroUary of the conception of " psychological 

 levels " formulated by the author in his book Instinct and 

 the Unconscious. 



Dr. Rivers's early death, that has caused so great a 

 loss to English psychology, left the present work un- 

 finished, and it is almost certain that he would have 



considerably altered and modified the latter part of it. 

 As it stands, it is of the highest interest to the speciaUst 

 and a valuable commentary for the general reader who 

 is acquainted with the Freudian theories, but may 

 perhaps have remained unaware of any alternati\-e 

 explanation of the phenomena with which they deal. 



F. A. H.^.MPTOX. 



BOOKS ON SCIEN'CE 



Metals and Metallic Compounds. By Click R. Ev.^xs, 

 JI.A. Four Volumes. (Edward Arnold i.t Co., 21s., 

 iSs., 14s., and 185., respectively.) 



Tliis is a comprehensive work on the chemistry and 

 the physical chemistry of those elements which are 

 usually regarded as metals. It is not so detailed as the 

 many-volume treatises of Newton Friend and Mellor, 

 and differs from these works not only by its omission 

 of an account of the non-metallic elements, but also by 

 its emphasis on metallurgy' and on such subdivisions of 

 physics and chemistry as pertain to that subject. The 

 first volume, which no doubt caused the author most 

 trouble, and which is very good, deals with general 

 chemistry, the study of the metallic state, electro- 

 chemistry, the corrosion of metals, and radio-activity. 

 \'olume II deals with the metals of the " A " Group, 

 \'olume III with the transition elements, and \'olume IV 

 with the metals of the " B " Group. The space devoted 

 to each metal is divided into three main sections. The 

 first gives an academic description of the metal and its 

 compounds and contains a summary of the methods of 

 analysis. The second section deals shortly with the 

 terrestrial occurrence of the metal in question, starting 

 with its origin in the rock-magma, and discussing the 

 probable mode of formation of the chief ores and minerals. 

 The third and longest section is of a technical character- 

 The author starts with the ore, follows the metal through 

 the processes of concentration and smelting, and finally 

 considers the practical uses of the element, its alloys 

 and its compounds, trying throughout to make this 

 section a correct sur\-ey of industry carried on at the 

 present time. 



A be ok like this one, written obviously to be of use to 

 readers and not to placate imagined critics, which avoids 

 going into the history of e\ery detail as large treatises 

 tend to do, and which gives sufficient references to the 

 literature and sufficient credit to the more prominent 

 workers without surrounding the facts in a sea of proper 

 names, will of course find an audience. It should be 

 useful to advanced students of inorganic and metallurgical 

 chemistry, to engineering and industrial chemists, and 

 indeed to all students of the book's subject-matter who 

 have not the works of Dr. Mellor or Dr. Newton Friend. 

 The chief criticism I ha^■e against the book is that it 

 contains matter which is not only irrelevant to the 

 author's subject, but which is better described elsewhere. 

 The sections in the introductory chapter dealing with 

 analytical chemistry, with radiation and chemical equili- 

 bria might well have been omitted. And what has radio- 

 activity, well though it is summarised, or the fractiona- 



