A Preliminary Revision of the North American Species of Cactus, Anhalonium, and Lophophora. E-book. Formato PDF John Merle Coulter   -  Ionlineshopping.Com, 2019  - 

In the proposed preliminary account of the family, of which the present paper is the first part, only those genera are considered which form a part of the flora of the United States, and those species which I have been able to examine and to identify with reasonable certainty. All forms credited to the United States have been studied, and the account of these species may be considered fairly complete, but the far more numerous Mexican species are but scantily represented. The Mexican boundary is so unnatural a dividing line in the distribution of Cactaceae that it has been disregarded, and all the species studied have been arranged in a lineal series of uniform prominence. So far as known the subject of geographical distribution is considered, but it will be seen how meager is our knowledge of this subject. It is to be hoped that this preliminary presentation will provoke exploration and study, and that species will not only be collected, but all the facts of their distribution noted. It is more than probable that our present notion of species in this group must be much modified, and doubtless many forms are at present kept specifically distinct which will prove to be but different phases of a single species.  

Evolution, Heredity and Eugenics. E-book. Formato PDF John Merle Coulter   -  Forgotten Books, 2017  - 

The text is organized into what have been tested and found to be serviceable assignment units short chapters which may also be welcome to the general reader. Chapters 21 to 24 are by Dr. S. W. Williston, of the Uni versity of Chicago. Acknowledgment is made of the cour tesy of the American Book Company in connection with the use of illustrations that are on pages 95, 96, 101, and 107.