1896. SOME NEW BOOKS. 129 



the second year. If a writer chooses to adopt the role of a popular 

 teacher, it is not too much to expect that he will first consult the 

 literature of his subject ; but we would prefer to leave the task of 

 fault-finding to somebody else. The real, transcendent merit of the 

 work lies in the splendid plates with which it is adorned, two of which 

 we are enabled to reproduce through the kindness of the publishers 

 (see Pis. III. and IV.). It is easy to take photographs of birds' 

 nests. It is most difficult to secure satisfactory results. Only those 

 of us who have plodded up and down the mountain sides, with 

 camera and tripod on the shoulder, can comprehend the vast amount 

 of trouble needed to obtain such a noble- series of negatives as those 

 which Mr. C. Kearton has actually developed. Not only so, but our 

 authors have set to work with a fine, artistic perception of the 

 beautiful. No one can turn over the pages of this volume without 

 feeling grateful to these spirited nest-hunters for the delicious insight 

 into the habits of wild birds which their pictures afford. 



H. A. Macpherson. 



Dubois on Past Climates. 



The Climates of the Geological Past, and their Relation to the 

 Evolution of the Sun. By Eug. Dubois. 8vo. Pp. viii., 167. London: 

 Swan Sonnenschein & Co., 1895. Price 3s. 6d. 



The author tells us in the preface that "The present essay is an 

 attempt to explain by changes of the solar heat the great climatic 

 changes of the Geological Past." It is a translation, with some small 

 alterations, of a treatise in German, " Die Klimate der geologischen 

 Vergangenheit, und ihre Beziehung zur Entwickelungsgeschichte der 

 Sonne," which appeared in the beginning of 1893 (Nijmegen: H. C. A. 

 Thieme). In the first part of the book we have a general account of 

 the climates of the past ; in the second, a discussion of the " changes 

 in the solar heat as the agency by which the geological climatic 

 changes were brought about." At the outset the author discusses 

 the difficult question of fossil plants and animals as indices of climatic 

 changes in past time ; the subject-matter of this part of the essay is 

 practically the same as that treated of in the Sedgwick Essay of 1892. 1 

 Dubois wisely points out the danger of relying too closely on 

 organisms as safe guides in questions of climate. He writes : " A 

 fixed relation between the climate and the character of the organic 

 world does not exist." After speaking of the spreading of northern 

 forms towards the south, and their gradual acclimatisation to new 

 conditions, he adds : " In this way southern types will always display 

 a certain relationship to the older forms of the northern regions, the 

 cause of which is thus not to be found in a change of temperature in 

 their respective stations." The arctic floras are briefly dealt with, 

 and the familiar conclusions drawn as to Tertiary climates. In 

 speaking of the Carboniferous vegetation, the author refers to the 

 preponderance of marattiaceous ferns among the Coal period Filicinae ; 

 it should be borne in mind, however, that the Marattiaceae at the 

 present day are very few in number, and confined to tropical regions. 

 It is hardly safe, therefore, to compare the living remnants of this once 

 vigorous and widespread family with the Marattiacea: of the Carboni- 

 ferous forests as regards climatic conditions of growth. 



Other authors have suggested that the Glossoptcris flora of the 

 Southern Hemisphere, which appears to have replaced the charac- 

 teristic Coal flora towards the close of the Palaeozoic period, owes its 



1 " Fossil Plants as Tests of Climate." A. C. Seward. London : 1892. 



