^T The Pi.ant World. 



He defines autometamorphism as the possession by a seed, 

 in itself, of the essential nature (I'instinct) of the family or genus 

 to which it belongs. While mutation accounts for the origin 

 of varieties and forms, autometamorphism enables us to deter- 

 mine the properties of species and to recognize their affinities 

 and true stocks. Autometamorphism may be said to be a cen- 

 tripetal force, and mutation a centrifugal. 



The author holds that there are certain primordial species, 

 the only ones existing in nature, represented by a few types; 

 the difficult thing being to disentangle these from the innumer- 

 able products of mutation and hybridization, which authors 

 wrongly raise to the rank of species. 



"M. Hugo De Vries," concludes the Abbe, "has codified 

 horticultural practices and clothed them in scientific formulas, 

 something which no one before him had ever dreamed of doing; 

 he explains the origin and establishment of races; that of species 

 remains a problem." 



THE EFFECT OF MOISTURE ON THE GROWTH OF 



USNEAS. 

 By R. Heber Howe, Jr. 



Mr. A. W. C. T. Herre, in the Plant World (12:257. 1909), 

 criticizes my statement that the "great luxuriance of Pacific 

 coast specimens, (is) due evidently to abundant moisture." 

 (Bull. Torr. Bot. Club 36:315. 1909). He writes:" This is not 

 so evident to those of us who live at present on the Pacific Coast 

 and who are familiar with the flora of all parts of the United 

 States; it may be true of some species perhaps, but it certainly 

 is not true of the Usneas of which he is speaking. One could 

 hardly be so sure of abundant moisture when six or seven months 

 often pass without rain, the annual precipitation of 15 to 40 

 inches coming during the winter months. It is true that there 

 are some summer fogs, but they lack much of supplying adequate 

 moisture, though of course they have an appreciable eflfect upon 

 vegetation. The aridity of California in general is shown by her 

 xerophytic forests and impenetrable gnarled chaparral, and by the 

 great number of endemic xerophytic lichens, such as Heppias and 

 Acarosporas, 



