144 



normal trees acting as controls under similar growth conditions. 

 The term mutation may be conveniently applied to the sudden 

 appearance of an inheritable peculiarity, whether due to an 

 immediately preceeding change in the germ plasm or to the rare 

 kaleidoscopic combination of unit characters already present. 

 The form variant of the sugar maple here described therefore, 

 may be provisionally classed as a mutant. 



A CLASSIFICATION OF BOTANICAL SCIENCE IN TWO 



DIMENSIONS 



By Roland M. Harper 



The classifications of knowledge relating to the vegetable 

 kingdom which one finds in encyclopedias, text-books, library 

 manuals, etc., usually arrange the ultimate units in a linear 

 sequence (a space of one dimension), and almost necessarily so, 

 for the parts of a written or spoken discourse, such as a lecture 

 course, are consecutive rather than simultaneous. But a classi- 

 fication of science, books, plants, life-zones, or anything else, 

 that has but one dimension can not as a rule place all the units 

 in their proper relation to each other, for in a linear sequence 

 each unit can be adjacent to not more than two others.* 



An ideal classification should have several dimensions, but 

 any system represented on a sheet of paper or other plane surface 

 is limited to two. This answers fairly well for classifying sci- 

 ences, though, for it allows us to classify them by subject matter 

 and by point of view at the same time. 



The subjoined table represents a crude attempt to arrange the 

 botanical sciences in two dimensions. The columns represent 

 the objects studied, and the horizontal divisions the points of 

 view or methods of investigation. The columns form a regular 

 series of increasing complexity, from vegetable matter in general 

 to plant associations ; but there is no such simple relation between 

 the horizontal rows, and if a third dimension were available the 

 points of view might advantageously be grouped in two dimen- 

 sions instead of one, so as to bring the study of environment, 



* One of the latest and most elaborate linear classifications of pure and applied 

 botany is that of Harshberger in Science, II. 36: 521-525. Oct. 18, 1912. 



