Geology and Natural History. 85 



of it certain positions were taken which were later shown to be 

 untenable. From these positions, Professor Bateson has retreated 

 gracefully. In the present treatise he has endeavored to present 

 some of the more important facts relative to the study of certain 

 types, and this necessarily involves much condensation. It is 

 just here that the work strikes us as excellent in all respects. To 

 select from the rapidly accumulating stores of facts those 

 which are most telling, and to set these forth in a short yet clear 

 manner, is a task of great difficulty. It must not be expected 

 by the casual reader that a work on a topic so vast and recondite 

 as this will prove easy reading; it is not: but it is straightfor- 

 ward and free from unnecessary complications. Professor Bate- 

 son has here given some of the more interesting as well as 

 important studies in animals and plants, and has devoted a con- 

 siderable part of his space to color and color-ratios. It is this 

 which will open up to young naturalists an absorbingly attractive 

 field for original investigation. When one recalls the admirable 

 work which has been done by amateurs in the study of the rela- 

 tions of flowers to insects, it is not difficult to believe that this 

 neighboring field may receive assiduous cultivation at their 

 hands. To such, as well as to professional biologists, Professor 

 Bateson's work will serve as an admirable guide, safe in all 

 respects. There is only one word of caution to those entering 

 this field of study: be as sure as you can that you know the 

 source of the material which you have under investigation. Do 

 not forget — what is too often forgotten — the difference between a 

 species and a race, and do not confound species-hybrids with the 

 crosses between races and between varieties. We do not mean, 

 of course, that we can as yet distinguish in all cases between 

 species and races, but we can at least choose as material 

 those plants about which there is comparatively little question. 

 In these days, when some of our polymorphous genera of plants 

 are in a state of disintegration, there is a large amount of good 

 material to be had. g. l. g. 



12. Contributions from the Gray Herbarium of Harvard 

 University. New Series, No. XXXVI, May 1909. — This number 



is given up to Mexican and Tropical American Phanerogams, and 

 comprises eight papers. Miss Alice Eastwood gives a synopsis 

 of the Mexican and Central American species of Gastilleja, 54 

 in all. Professor Robinson deals with the genus Rumfordia and 

 with a number of tropical phanerogams, some of which are new 

 and are now for the first time described, while others are trans- 

 ferred to their proper place in the system. Mr. H. H. Bartlett 

 treats of the American species of Litsea, the Mexican and Central 

 American Alders, the southern Androcerae, and certain other 

 southern flowering plants. These papers are published as No. 21 

 of Vol. XLIV of the Proceedings of the American Academy of 

 Arts and Sciences, Boston. g. l. g. 



13. Elemente der exakten Erblichkeitslehre, von W. Johann- 

 sen, Professor in Kopenhagen. Pp. vi, 515. Jena, 1909. (Gus- 



