6o4 



NA TURE 



[April 26, 1906 



the department of double and variable stars. Into the 

 significance of variable, and especially of " new stars," 

 the author does not enter. Doubtless he is well 

 advised in considering the introduction of such topics 

 premature, but the omission shows that we have a 

 certain class of facts which cannot yet be brought 

 into line with other data. We have not yet succeeded 

 in weaving our information into a consistent whole. 



In the second section we have the results of observ- 

 ation mainly as exemplified in the production of star 

 catalogues, whether of place or of spectrum, of 

 brilliancy or of distance, for in these catalogues, 

 applying, as they do, to large areas in the sky, must 

 be contained the information which is to solve the 

 problem of the universe. No inconsiderable portion of 

 this section is occupied with the question of proper 

 motion and the proper method of its treatment. Here 

 we have raised for us, in an acute form, the question 

 of the parallactic as distinguished from the actual 

 motion of the star, and the legitimacy of the assump- 

 tion as to the absolute lawlessness of direction of the 

 star's own motion. On this and similar points a 

 certain amount of controversy exists, and Dr. Kobold 

 is known to hold very definite views. Fortunately we 

 do not consider it necessary to enter into any of these 

 differences of opinion. We are simply concerned in 

 pointing out the general direction to which the com- 

 bined information points, and its bearing upon the 

 existence of a stellar system. These conclusions Dr. 

 Kobold collects in his third section, and, greatly 

 daring, has summarised " on half a sheet of note- 

 paper." This statement is so succinctly expressed that 

 it may be reproduced almost literally. Through- 

 out a finite space of spherical form are scattered bodies 

 very different in mass and in physical conditions. 

 With gaseous nebulae at very low temperature occur 

 other bodies in a condition of glowing heat and 

 advanced condensation. The arrangement of the 

 separate masses is not uniform ; they are crowded 

 together in clusters about certain centres of con- 

 centration. These groups possess a loose relation- 

 ship, and are arranged in the form of a spiral having 

 many branches. In the more distant parts of this 

 spiral the hotter and gaseous stars predominate. The 

 sun is comparatively near to the centre of this spiral, 

 and the stars which stand in closest connection with 

 it have also similar physical conditions. On the sun 

 is impressed a motion towards a point in the Milky 

 Way, the principal plane of the whole spiral, and a 

 great number of stars near the sun participate in this 

 same motion. Among the stars there are numerous 

 groups having an apparent motion directed to points 

 in the Milky Way. The stars of each group are in 

 one plane, and their true motion, on the character 

 of which definite information is still wanting, takes 

 place in this plane. 



This may seem a very small outcome for so much 

 work, but it will hardly be urged that the author has 

 erred on the side of caution. In any case this 

 " Schlusswort " is valuable, since it expresses the 

 opinion of one who is especially qualified to speak 

 on a subject which possesses in an equal measure 

 both interest and difficulty. W. E. P. 



NO 1904, VOL. 73] 



A PHYSIOLOGICAL STUDY OF THE 

 BRITISH FLORA. 

 British Floivering Plants. By the Right Hon. Lord 

 Avebury. Pp. xxiii + 450. (London: Macmillan 

 and Co., Ltd., 1905.) Price 155. net. 



LORD AVEBURY has given us in the past 

 several delightful books on botanical subjects, 

 dealing more especially with the forms and functions 

 of leaves, flowers, and fruits. At the time when the 

 earlier of these books were published there was a 

 tendency to reduce botanical morphology to a cut-and- 

 dried series of shapes and forms, each designated bv 

 a Latin name the correctness of which received more 

 attention than the purpose served by the various 

 modifications. In " Flowers, Fruits, and Leaves," 

 and " British Wild Flowers in Relation to Insects," 

 Sir John Lubbock adopted the more natural treatment 

 of studying form in the light of function, with the 

 result that on account of their broad conceptions and 

 the appeal they made to the reasoning faculty, these 

 books obtained a wide circulation, and even now they 

 maintain their position among the foremost contribu- 

 tions to the subject. In the circumstances the author 

 has drawn freely from his previous works in writing 

 this volume, which is restricted to British plants, and 

 contains shorter or longer references to all our 

 flowering plants. It provides, therefore, a running 

 commentary to British floras in general and to 

 Bentham's " British Flora " in particular. 



On the details of buds and stipules, a subject that 

 Lord Avebury has studied very carefully, much in- 

 formation is provided. In the genus Lathyrus the 

 shape of the stipules v;irics from the large foliaceous 

 type of Lathyrus tnaritimus through the narrow sagit- 

 tate stipules of Lathyrus pratensis to the minute, 

 slender stipules that occur in Lathyrus nissolia. 

 These and other forms found in the genus are col- 

 lated, and it is pointed out how the shape fits in with 

 the attachment of the leaf to the stem. The complex 

 nature of the stipules of the hawthorn also receives 

 elucidation. A full account is given of the winter 

 buds of the beech, the pine, and the spruce. It will 

 be seen from these that the examination and dissec- 

 tion of the winter buds of trees and shrubs provide 

 a capital exercise for a nature-study class. Consider- 

 able attention has been paid to the dichogamous and 

 diclinous conditions of flowers. The ordinary straw- 

 berry furnishes a good instance. Darwin distin- 

 guished female flowers producing plenty of fruit, 

 complete flowers less fertile, and male flowers natur- 

 ally bearing no fruit. Schulz observed for the same 

 plant gvnomonoecious, andromoncecious, gyno- 

 dicecious, and androdioecious forms. This is only one 

 of several types of variation in the flower that too 

 frequently pass unnoticed. A certain amount of work 

 has been published on floral variation, more recently 

 by students of biometric problems, but there is plenty 

 of opportunity for observations continued over a series 

 of generations to obtain more definite conclusions on 

 the subject of small variations. 



An introductory chapter deals with categories and 

 types, ar for instance, flowers of water plants, 



