Nff 



27, 190S] 



SCIENCE 



771 



color drawings. A good index closes this vol- 

 ume, wliicli must prove very useful to tourist 

 or botanist in the Canadian Eoeky Mountains. 



oecutt's ameeica^t plants 

 Few eastern botanists can realize the dif- 

 ficulties of the student of systematic botany 

 in the far west, where there are no handy 

 manuals containing the descriptions of all 

 the flowering plants and ferns and in some 

 eases plants of lower groups also. For some 

 years Mr. C. E. Orcutt, of San Diego, Cali- 

 fornia, has attempted to remedy this condi- 

 tion by bringing together the descriptions of 

 genera and species of south Calif omian 

 plants. "We have often wished that his type 

 and paper were better, but work of this kind 

 is a labor of love, and in the absence of an 

 endowment must be brought out at the least 

 possible expense. It is greatly to ilr. Oreutt's 

 credit that he has been able to bring out 

 this book of nearly two hundred pages of 

 descriptions, many of which occur in widely 

 scattered publications. From the title-page 

 we learn that the volume contains " descrip- 

 tions of over 200 genera, more than 1,200 

 species and many varieties." A second vol- 

 ume is in preparation, at the close of which 

 we are promised an index to the two volumes. 

 This win make the work much more useful, 

 for with no index it is well-nigh impossible 

 to find any particular description without the 

 expenditure of m.uch time. VV ben these de- 

 scriptions are all brought out, they should be 

 put together in the form of a systematic 

 manual of the plants of southern California. 



A HIGH-SCHOOL BOTA]<IT 



!N'oTicE shoiild be made here of Coulter's 

 text-book of botany for secondary schools re- 

 cently brought out by the Appletons in the 

 excellent type, paper and presswork which is 

 characteristic of their publications. The plan 

 of the book is that which has been generally 

 followed in recent years. There is first a 

 general part (less than one hundred pages) in 

 which gross and microscopical anatomy are 

 taken up by the pupil, and this is followed 

 by chapters on algae, fungi, liverworts, mosses, 

 ferns, horsetails and club-mosses, gynmo- 



sperms and angiosperms, nearly one hundred 

 and fifty pages being given to an admirable 

 treatment of the morphology and general 

 classification of the plants of these groups. 

 Then follow two chapters (20 pages) on 

 flowers and insects, and seed dispersal, and 

 then 61 pages on the structure and classifica- 

 tion of monocotyledons and dicotyledons. 

 The remainder of the book (about 40 pages) 

 is given to little snatches of discussions of 

 plant breeding, forestry, plant associations, 

 hydrophytes, serophytes and mesophytes. 

 Some of these closing chapters could well be 

 omitted, since the necessarily brief treatment 

 is wholly inadequate. However, taken as a 

 whole the book is one of the best of those 

 adapted to Tise in the high schools. 



Charles E. Bessey 

 The Univeesitt of Nebraska 



SPECIAL ARTICLES 



MEKDELlUf HEREDITT 



One might suppose, at first thought, that, in 

 cases of Mendelian heredity, the dominant 

 form would be capable of gaining over the re- 

 cessive in the course of evolution, merely 

 from the nature of the dominance. The 

 falsity of this view was well shown by Shull 

 (1907) and more recently by Hardy (1908). 

 The successful increase of a mutation depends 

 upon aid from determinate evolution or 

 natural selection. Here we are only con- 

 cerned with the work of the latter. 



Shull maintains that the view that reces- 

 siveness is a handicap is quite erroneous ; " not 

 only has the dominant form no advantage in 

 the competition which the newly arisen ele- 

 mentary species m^ust encounter, but it can be 

 shown that under certain conditions the re- 

 verse is true." He then clearly shows that, 

 where the new characteristic has less favor- 

 able chances of survival at the time, lecessive- 

 ness is an advantage, for it may be shielded 

 from extermination by being carried without 

 somatic expression. 



But if we assume the opposite condition, 

 namely, that the new characteristic is more 

 favored tba-n the parent species, then domin- 

 ance gives an advantage because the char- 

 acteristic will be present in each generation. 



