80 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



them, so fixed do they become on the young mind. One could wish some- 

 times that authors would realize the impressiveness for many minds that 

 still clings round the printed word, and would therefore, in their popular 

 writings, be chary of advancing theories without carefully testing them 

 from many points of view. 



The illustrations, numbering 120, form a feature of the book and are 

 good photographs well reproduced in half-tone. Most of them are worthy 

 of praise, though figure 84 does not show the blotches on the Orchis leaves, 

 which it is said to depict. Figure 93 appears to represent Sedum spectabile, 

 not S. Telephium, as the name is given in the text. 



" The Methods and Scope of Genetics." By W. Bateson, M.A., 

 F.R.S. 8vo., 49 pp. (University Press, Cambridge, 1908.) Is. 6d. net. 



It was a happy idea of Professor Bateson to publish, for the benefit of 

 the general public, the lecture which he delivered before the members of 

 the University of Cambridge on the occasion of his inauguration as 

 Professor of Biology in October last. 



The purpose of the lecture is to describe, in a popular manner, the 

 present outlook over the field of experimental research in the physiology 

 of heredity and variation, a study which, owing to Mendel's wonderful 

 discovery, has now developed into the definite and distinct science known 

 as Genetics. As the author says, Mendelian discovery is leading us into 

 a new world, the very existence of which was unsuspected before. He 

 begins by pointing out the simple fact that each individual plant and 

 animal has a double nature owing to its origin from two cells, one 

 maternal and the other paternal. It is curious that the full consequences 

 of this double nature seem to have struck nobody before Mendel. As 

 Professor Bateson says : " In order to understand the significance of 

 Mendelism, we must get thoroughly familiar with the fact that a man, 

 a butterfly, and an apple-tree are not each one thing, but are each two 

 things, double throughout every part of their composition. Consequently 

 the contribution of the maternal and paternal gametes, or ' marrying ' cells, 

 may, in respect of any of the ingredients, be either the same or different. 

 If they are the same the regulating organism is pure-bred for that 

 ingredient ; if different it is cross-bred." 



Recent genetic research has led us to the further important conception 

 that the individual is composed of what we call " presences " and 

 "absences" of all the possible ingredients. This fruitful conception is 

 the basis of all progress in genetic analysis. As to the nature of these 

 ingredients or factors we at present know nothing, but it is interesting to 

 note that Professor Bateson thinks that with the assistance of the physio- 

 logical chemist, it cannot be very long before we know what some of 

 these factors are. 



Professor Bateson next deals with the phenomenon of segregation, 

 and shows that where an individual is cross-bred for a certain ingredient, 

 the germ-cells formed by such an individual alternately either contain or 

 do not contain representatives of that ingredient. In Professor Bateson's 

 own words : " If both the parent-gametes brought a certain quality in, 

 then all the daughter-gametes have it. If it came in from one side and not 

 from the other, then on, an average, in half the resulting gametes it will 



