Supplement to ''Nature'^ September 15, 192^ 



423 



civilisation in Egypt arose in the Delta, and that it 

 spread up the river. Before ■ Menes conquered the 

 north there had been a kingdom of Middle and Upper 

 Egypt, and before that a kingdom with its capital at 

 Sais in the North-Western Delta. The people of the 

 _North- Western Delta were closely connected with the 

 irly Cretans, and were of the same race as the pre- 

 lastic people of Upper Egypt. In the Eastern 

 |elta at an early period lived a pastoral clan that 

 id come in from Western Asia and brought into 

 ilgypt the domesticated goat and sheep, as well as two 

 important cults connected with trees that were not 

 indigenous to the soil of Egypt. The absence of timber 

 : trees makes it doubtful whether the art of the carpenter 

 [arose in the Nile Valley. Architectural styles founded 

 Ion wood construction cannot well have originated in 

 a timberless country, nor could the art of building 

 : sailing or sea-going ships. It may be doubted that the 

 custom of burying the dead in wooden cofifins arose in 

 Egypt ; the resins used in embalming were not native 

 to the Nile Valley. No incense trees or shrubs are 

 known in Egypt, hence it is probable that the cere- 

 monial use of incense did not arise there. Such are 

 some of the anthropological questions raised by a 

 study of the flora of the Lower Nile Valley. 



Symbiosis in Animals and Plants. 



Prof. George H. F. Nuttall's address to Section I 

 (Physiology) dealt with (i) Symbiosis in plants : 

 lichens ; root-nodules of leguminous plants ; the 

 significance of micorhiza in various plants, especially 

 orchids ; and (2) Symbiosis in animals : Algae as 

 symbionts in various animals ; symbiosis in insects ; 

 micro-organisms in relation to luminescence in animals. 

 The subject is one of broad biological interest, an 

 interest that should appeal equally to the physiologist, 

 pathologist, and parasitologist. It is a subject on 

 which much work has been done of recent years, and 

 information relating thereto lies scattered in the 

 scientific literature of different countries. 



The term symbiosis denotes a condition of conjoint 

 life existing between different organisms that are 

 benefited to a varying degree by the partnership. 

 The condition of life defined as symbiosis may be 

 regarded as balancing between two extremes, complete 

 immunity and deadly infective disease. Symbiosis 

 has doubtless originated from parasitism. One condi- 

 tion merges into the other, there being no line of 

 demarcation to separate them. Some organisms sup- 

 posed to be symbionts to-day may prove to be parasites 

 on further investigation. Certain structures that have 

 been described in the past as normal intracellular bodies 

 in animals and plants have in a number of cases been 

 shown to be micro-organisms which can be cultivated or 

 symbionts that are transmissible hereditarily from host 

 to host. The address constitutes a summary of what 

 is known to-day of symbiosis in the animal and vege- 

 table kingdoms. Apart from its scientific interest, 

 the economic importance of studies on symbiosis is 

 exemplified by what has been established, on the 

 botanical side, with regard to the root-nodules of 

 leguminous plants, the germination of orchids, and the 

 origin of tubers. 



Mental Differences between Individuals. 



The address by Dr. Cyril Burt, president of Section 

 J (Psychology), deals with the mental differences be- 

 tween individuals, with special reference to applied 

 psychology in education and industry. The most 

 remarkable advances made by psychology during 

 recent years consist in the rapid development of what 

 threatens to become a new and separate branch of 

 science ; namely, the study of individual differences 

 in mind. The numerous data collected from various 

 fields of applied psychology — from the psychology of 

 education, industry, and war, of mental disorder, 

 deficiency, and crime — are now sufficiently extensive 

 and trustworthy to deserve co-ordination into a single 

 systematic body of knowledge. 



Early pseudo-scientific attempts to diagnose mental 

 characteristics from physical and other signs were 

 misled by an inadequate technique. The true pro- 

 cedure was supplied by Sir Francis Galton, who applied 

 to the general problem two special methods of inquiry — 

 the statistical method of correlation, and the experi- 

 mental method of psychological tests. These in turn 

 rest upon a fundamental assumption, which recent 

 work has verified — the continuity of mental variation. 

 This is the keystone of individual psychology as a 

 science. The differences between one man and another 

 are always a matter of " more or less," seldom, if ever, 

 a question of presence or absence or of " all or none." 

 There are no such things as mental types ; there are 

 only mental tendencies. 



The general scheme under which individuals are to 

 be studied is much the same, whether they are normal 

 or supernormal, backward, defective, or delinquent, 

 or ordinar}' applicants for vocational guidance. 



The positive foundations for a practical psychology 

 of individual differences have been laid in three broad 

 generalisations, each the separate suggestion of recent 

 experimental work. These consist in a trio of important 

 distinctions : the distinction between intellectual and 

 emotional characteristics, between inborn and acquired 

 mental tendencies, and between general and special 

 capacities. The future progress of individual psycho- 

 logy will consist chiefly in devising more exact methods 

 for examining mental qualities under each of these 

 respective heads. 



Aspects of the Study of Botany. 



Mr. a. G. Tansley's presidential address to Section 

 K (Botany) deals with some aspects of the development 

 of pure botany during the last thirty or forty years, 

 especially in the British Isles. By means of quotations 

 from representative botanists of the last decade of last 

 century, the views held at that time on the relation of 

 morphology and physiology — that they were two 

 independent " disciplines " or branches of botany — 

 are illustrated. It is pointed out that little progress 

 has been made towards realising the idea of determining 

 the " genealogical tree " of the plant kingdom, and 

 this not so much from the fact that our knowledge is 

 still incomplete, as because, in the recent words of a 

 great authority, it has become evident that the past 

 development of the plant kingdom is represented by 



