58 



SCIENCE 



[N. S. Vol. XXXIV. No. 863 



Leipzig u. Berlin, B. G. Teubner. Pp. iv + 



436, 159 figs.; 2 pis. 1911. 



The large amount of literature which has 

 been produced on the mutualistic relations of 

 flowers and insects by Sprengel, Darwin, 

 Delpino, Hildebrand, H. Miiller, E. Loew, 

 Chas. Robertson and numerous other investi- 

 gators, and especially the recent publication 

 of Knuth's exhaustive " Handbuch der 

 Bliitenbiologie " and its translation into 

 English, would seem to render super- 

 fluous any further general presentations 

 and to leave room, at least for some years 

 to come, only for very special studies. An 

 examination of von Kirchner's volume, how- 

 ever, shows it to be a very concise and useful 

 compendium. The author presents the ento- 

 mological aspect of the subject more fully 

 than is usually attempted in similar works, 

 one whole chapter being set aside for this 

 purpose, after an introduction and two chap- 

 ters on the meaning of pollination, the vari- 

 ous ways in which it is brought about and 

 the peculiarities of insect pollination, or ento- 

 mogamy. Then follows a chapter on the gen- 

 eral adaptations of flowers to insects. The 

 bulk of the work is devoted to a concise and 

 interesting discussion of the various types of 

 entomogamy (Chapters VI. to XII.) accord- 

 ing to H. Miiller's classification of flowers 

 into those which bear pollen only and those 

 which produce nectar, and of the latter into 

 various subgroups according to the accessibil- 

 ity of their nectaries or the peculiarities 

 which make them specially attractive to 

 Diptera, Hymenoptera or Lepidoptera. The 

 ability of the author to present matters 

 clearly and briefly is well shown in his ac- 

 count of the classical cases of the yucca moth 

 and the caprification of the fig, while his bal- 

 anced and temperate judgment finds expres- 

 sion in the three concluding chapters of the 

 work, which deal with floral statistics, the 

 causes of the mutualistic adaptations of 

 flowers and insects and the various hypoth- 

 eses which have been advanced to account for 

 the phylogenetic origin and development of 

 floral structures. That rare thing in so many 

 recent German books, a good index, is added. 



The text is well-illustrated with a number of 

 large clear figures, mostly from drawings by 

 the author. A few of these figures, however, 

 are open to criticism, for example, Fig. 16, 

 which represents the abdomen of the bee 

 Osmia spinulosa, is up-side-down, and Eig. 10, 

 representing the olfactory organs of insects, 

 is woefully archaic and should be replaced in 

 a future edition by an up-to-date illustration. 

 It is to be hoped that von Kirchner's work 

 will be translated into English so that it may 

 become more useful to students in the United 

 States and inspire further observations on 

 the mutualistic relationships of our native 

 flora and insect fauna. 



W. M. Wheeler 



SPECIAL ARTICLES 



A NEW SPECIFIC GRAVITY BALANCE 



The Specific Gravity of Minerals. — As the 

 specific gravity is one of the most constant 

 properties of minerals, its determination for 

 pure massive specimens is one of the best 

 means of identification. The accurate deter- 

 mination of specific gravity is a slow and 

 painstaking process. A simple and rapid 

 method which will give approximate results 

 suffices for many purposes. The Jolly spring 

 balance and a beam balance,^ which depend 

 upon the well-known principle of hydrostatics 

 that a substance immersed in water loses in 

 weight an amount equal to the weight of the 

 water displaced, are fairly satisfactory. Two 

 or three readings are made from which the 

 value of the specific gravity is obtained by 

 calculation. Though the calculation is simple 

 enough it takes time and one is apt to make 

 mistakes. The writer has designed a modi- 

 fication of the beam balance which it is be- 

 lieved will be found more convenient than 

 these other forms, as the specific gravity is 

 read off directly, the calculation being made 

 once for all and recorded as graduations on 

 the beam. 



The New Balance. — The accompanying fig- 

 ure, which is one sixth actual size, shows the 



* Brush-Penfield, ' ' Determinative Mineralogy, ' ' 

 sixteenth edition, p. 235. Geikie, ' ' Structural and 

 Field Geology," second edition, p. 428. 



