310 



JOFENAL OF THE BOYArj HORTICULTFRArj SOCTRTY. 



however, observe that De Vries' mutants are smiply what might be 

 expected in changing the conditions of liis Oenotheras from " ahnost 

 pure sand "to a " highly manured garden." Such was evidently the 

 direct cause of his mutants. 



With regard to natural selection as a factor of evolution, he would 

 see some use for it, although variations may be caused by a changed 

 environment; but Darwin separated these two factors. He said that 

 changed conditions induced " definite " or "indefinite" results- If 

 the former prevailed, then a new variety arises witJiout the aid of any 

 selection. Ecology has shown that this is all that is required; and 

 that no " indefinite " variations ever arise in Nature at alL 



With the above few criticisms the reader will find a vast amount of 

 information clearly put, and evolution substantiated. 



Studies in Seeds and Fruits." By H. B. Guppy. 8vo., 528 pp. 

 (Williams & Norgate, London, 1912.) 15s. net. 



This book is an " Investigation commenced as a study of the 

 rest-period of seeds ; but its course has often been determined by 

 small indications, the balance and the oven, aided by a sharp knife and 

 a pocket-lens, being the only means of research employed." Without 

 reading more than this first sentence of Chapter I., one asks, Why 

 has he not got anything to say of the chemistry of the resting period ' 

 and the importance of the microscope instead of a lens ? 



No one will deny the great value of the enormous labour and valu- 

 able results bestowed and registered on the water contents of seeds at 

 different periods; but the chemical question arises, What portion of the \ 

 loss of weight is due to respiration, to the loss of carbon besides water? ; 

 Can any seed live in a vacuum, and if so for how long a time? Again, 

 one of the many interesting studies which the author describes is the ' 

 coloration of seeds. How far the various colours are connected with I 

 enzymes in oxidizing processes one would like to know ; but a chemist ! 

 would find much help, we think, from Mr. Guppy 's researches. 



The wings of seeds and fruits are usually regarded as special ' 

 purposeful means of flight; but doubts have lorig ago been raised; for 

 while the familiar one of the dandelion impresses the imagination 

 strongly, far more of the Compositae are unprovided with this aid to ; 

 flight. Mr. Guppy comes to the conclusion that they are helpful in 

 supplying water to the seed in the growing state. 



The author quotes Goebel's view as follows: — "Many arrange- 

 ments which have hitherto been considered merely as a parachute- 

 apparatus on the ripe fruit are in my view to be considered as a trans- 

 piration-apparatus for the ripening fruit; and these subsequently can 

 be used for dispersal. ' ' 



Another curious discovery was that the ivy and oak can be more or 

 less viviparous; by the seed not entirely drying up, it retains its 

 growing properties in the seed itself. Illustrations show that the 

 embryO' of the ivy enlarges after the fruit is completed. 



The above will be gufficient to show that besides the many tables of 



