664 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



of Variation " ; " Environment and Acquired Characters " ; " Mendel's 

 Discovery " ; " ^ex " ; " General Considerations." A large amount 

 of subsidiary matter is discussed under each of the above headings. 

 Not only does the author endeavour to account for heredity by means 

 of the cellular machinery, but gives the various theories of others. 

 They are too speculative at present to be considered settled. 



The whole of the book is unfortunately marred by the author taking 

 no account of Darwin's alternative explanation of the origin of species 

 without the aid of natural selection. In the list of works, he only 

 gives the Origin &c 1859. He has evidently not studied the sixth 

 edition. Consequently, the author regards natural selection as always 

 necessary and all-sufficient; whereas Darwin says that when *Vde- 

 fmite results occur, natural selection is absent."* 



He refers all characters, hereditary or otherwise, as being " inborn. " 

 Of course the former are so; but if " acquired," and they reappear in 

 the offspring, they are due, he says, to " modifications of [hereditary?] 

 inborn characters "; but this does not seem to account for the first 

 appearance of a new character, when the parent did not possess any 

 inborn character which could be modified so as to reproduce it. For 

 example, the Virginia Creeper (Ampelopsis hederacea) forms adhesive 

 pads on the tips of its tendrils, but 07ily after contact with a wall. 

 It has no inborn characters to produce them spontaneously ; but its 

 ally, A. Veitchii, begins to develop them before any contact is made 

 at all. This seems to imply a totally new, inborn character. But 

 according to Weismann and the author, such an hereditary character 

 requires an already inborn character to be affected by the direct action 

 of the environment. As an illustration he takes what he calls " the 

 classical example of a scar on a nose." But scars and mutilations 

 are not varietal characters, and have nothing to do with the origin of 

 species, because they are not results of a response to the environments 

 which Darwin recognized as the sole source of variations. 



It is not sufficiently emphasized by the author and other writers that 

 when variations are discussed there is a great deal more than the mere 

 external forms of organs; for organs are made of tissues of various cell- 

 structures; their changes have to be accounted for. New cells assume 

 new shapes and uses. Hence the origin of variations must be traced 

 to the nucleus. Many researches are now being made to try and discover 

 the cell-machinery in which lies the potentiality of heredity, as well as 

 the vehicle of new adaptations with acquired characters. Many theories 

 are propounded. If the reader is interested in these speculations he 

 mxust refer to this and other books. It is, however, unfortunate that 

 so many of this class are written by zoologists, for plants are so 

 much easier to study and to be used for experiments. The authors 

 know next to nothing of the incontrovertible truths established by 

 ecologists. 



* Animals and Plants under Domestication, ii. p. 271, &c. ; Origin kc, 6th 

 ed. pp. 6, 72, 80, &c. 



