BOOKS REVIEWED. 



271 



As everyone who studies the subject will not fail to provide himself 

 with this most important and exhaustive work, we need not do more than 

 summarise the general contents. 



The first section is a summary of " The Historical Development of 

 Flower Pollination," in which Dr. J. G. Kolreuter is said to be the first to 

 make observations and to point out that visits of insects are necessary for 

 pollination. He commenced his investigations after 1786. At the same 

 time Sprengel began his observations, which he recorded on some 500 plants. 

 The second section begins on p. 28 on " The Present Standpoint of Flower 

 Pollination," containing two sections, as follows : — (I.) Survey of the 

 modes of pollination and of the distribution of the sexes. (II.) Autogamy. 

 (III.) Geitonogamy. (IV.) Xenogamy. (V.) Heterostyly. (VI.) Cleisto- 

 gamy. (VII.) Parthenogenesis. (VIII.) Flower-groups, viz. water-, wind-, 

 and animal-pollinated flowers. (IX.) Insects that visit flowers, of six 

 kinds. (X.) Methods of research in flower-pollination. Each of these is 

 treated exhaustively. On p. 212 begins the bibliography, which is con- 

 tinued to p. 372, being followed by a list of zoological works, and an index 

 of zoological names contained in them. 



"Notes on the Life History of British Flowering Plants." By the 

 Right Hon. Lord Avebury, P.C. 8vo., 450 pp. (Macmillan, London.) 

 15s. net. 



This book may be regarded as a companion volume to Bentham's 

 "Handbook of the British Flora." A student has presumably mastered 

 the structure of flowers, so as to know the species of British plants ; but 

 the "Notes," which Lord Avebury has collected, mainly from his own 

 acute observations, form a most interesting addition to the " Flora." He 

 introduces the student to biological and physiological phenomena, which 

 which are of far more interest than the mere knowledge of the names of 

 plants and their classification. 



The volume begins with an Introduction of 46 pages, which is followed 

 by notes upon all the species, in the usual order as arranged by Bentham. 

 The author rightly insists on the importance of combining biology with 

 classification, a plan Henslow followed in a less ambitious way in his 

 "How to Study Wild Flowers" (B.T.S.) ; but Lord Avebury has added 

 a great deal more, though here and there we do not quite see our way to 

 follow him. 



The following points were noticed on running through the book in a 

 general way : 



In explaining how " fives " arose in floral whorls which form the 2 5 

 plan of phyllotaxis, it should have been added that, when the spiral is 

 reduced to a plane, the law of decussation or alternation sets in, and 

 makes the whorls alternate in position. It is suggested that the dissected 

 leaves of submerged plants afford thereby a larger surface to the action 

 .of the water ; but if all the intercostal tissue is arrested in a leaf, only the 

 ribs and veins remaining, the entire surface is diminisJied. The real 

 cause is degeneracy, which applies to the whole plant, in consequence 

 of the protoplasm being surcharged with water : so that if this be 

 made denser with nutritive salts, osmose is set up, the protoplasm loses 

 its water, and then makes complete leaves under water. 



