212 REVIEWS. 



Dr. Macbride's narrative ; he says that " some if not all the 

 species of the genus appear to possess a kind of glandular 

 function," without mentioning those that have it, or the 

 absence of it in the only species growing around him at the 

 north ; and he adds that he " was entirely unacquainted with 

 this curious economy . . . when I published the first edition 

 of my ' Elements of Botany,' and even when I printed the 

 appendix (in vol. i.) to the second edition of this work." Now 

 his paper is dated September 11, 1811 ; and the volume 

 referred to, as just printed, is dated 1812. But Macbride 

 states that his observations were chiefly made 1810 and 1811 ; 

 he corresponded intimately with Eliott, through whom, if not 

 directly, his observations would probably find their way at 

 once to the Philadelphia naturalists. 



NAUDIN ON THE NATURE OF HEREDITY AND 

 VARIABILITY IN PLANTS. 1 



Why is it the nature and essence of species to breed true, 

 and why do species sometimes vary ? In other words, why is 

 offspring like parent, and when unlike in certain particulars, 

 what is the cause and origin of the difference? We com- 

 monly and properly enough take these two associated yet 

 opposed facts as first principles. But it is equally proper and 

 legitimate to enquire after the cause of them. 



M. Naudin, a good many years ago, took up the study of 

 hybrid plants, and followed up for a series of generations, 

 the course of life of certain self-fertile ones, notably of Datura. 

 We gave at the time an abstract of his observations of the 

 manner in which the characters of two closely related common 

 species, D. Stramonium and D. Tatula, were mixed, and in 

 which the characters of the two began to separate in the close- 

 bred progeny of the next generation, ending in a complete 

 division of the amalgamated forms into those of the two con- 

 stituent species after a few generations. 



1 American Journal of Science and Arts, 3 ser., xi. 153. 



