494 SCIENCE PROGRESS 



mixture is not a salt, while the subject is already overburdened with a vast 

 nomenclature which includes many unnecessary names. 



Five chapters axe devoted to the problem of sea salts, and they include 

 accounts of the synthetic work on the subject, of chemical and organic deposi- 

 tion in nature and the parts played by organisms therein, of the origin of 

 deposits formed under marginal conditions and also those formed in closed 

 basins, and finally of the so-called " cyclic " salts such as those of Sambhar 

 Lake. The discussion of the physical chemical aspect of the subject is 

 somewhat inadequate and much of the space which is given up to illustra- 

 tions of the organisms responsible for deposition would have been better 

 utilised in a further elaboration of the synthetic work. 



The remainder of the book is occupied by accounts of terrestrial salts, 

 of those of igneous origin, and of those formed by metamorphic agencies. 

 One chapter is devoted to that important group of salts which owe their origin 

 to the concentration of sea salt occluded in marine sediments during their 

 deposition ; on the basis of Lane's term " connate water " such salts are 

 termed " connate sea salts." The nitrates, the phosphates and the complex 

 borate salts are each considered in separate chapters. 



Although the book, as a whole, suffers to some extent from the author's 

 obvious intention to make it a students' textbook, it may be said to give 

 a clear and readable account of the subject. This is especially the case 

 with those parts of the text which are definitely geological ; the treatment 

 there is much more complete than in the more chemical portions where 

 there is a tendency to omit detail. The illustrations, especially the sketch- 

 maps and sections, are very useful, but the references, though abundant, 

 might be more complete ; there is a curious lack of system in the method of 

 giving the references. An elaborate index is appended. 



A. S. 

 BOTANY 



The Naturalisation of Animals and Plants in New Zealand. By The Hon. 

 G. M. Thomson, M.L.C. F.L.S. [Pp. x + 607.] (Cambridge : at the 

 University Press, 1922. Price 42s. net.) 

 The introduction and subsequent establishment or failure of plants and 

 animals in New Zealand affords a unique opportunity for the study of these 

 aspects of geographical distribution, since the process has for the most part 

 taken place during a period sufficiently recent to permit of investigation. 



Mr. Thomson's work is a presentation of the ascertainable data embodying 

 the results of painstaking research, and the 361 pages recording the actual 

 facts respecting animal introductions, and the 139 pages devoted to the 

 plants, constitute a mine of information from which the student of problems 

 connected with establishment and survival can quarry. 



In respect to Flora and Fauna alike the process of introduction has been 

 an epitome of the effect of human interference on the balance of power as 

 exemplified by wild Nature. 



Many of the species owed their introduction to the numerous acclimatisa- 

 tion societies of the 'sixties and the early immigrants desirous of having around 

 them the animals and plants of the homeland. Not till too late was the 

 lesson learnt that the balance of Nature cannot be disturbed with impunity. 

 The rabbit, at first difficult to establish, developed into a plague, the sparrow 

 became a feathered pest. Similarly in the vegetable world the blackberry and 

 the sweet briar, both intentionally introduced, became noxious weeds no less 

 harmful than the thistle Cnicus arvensis. 



Cats, ferrets, stoats, and weasels have all been introduced to keep the 

 rabbit plague in check, whilst the goat was encouraged with a view to com- 

 bating the growth of blackberries. Each in turn has become itself a nuisance, 

 whilst in some cases the pest which it was intended to destroy has been 

 neglected for another source of food. 



