NOTES. 



1. That branch of natural science which treats of the adaptations of organisms 

 is often termed " biology " ; some critics of the first [German] edition of the present 

 work have remarked that the term " physiological plant-anatomy " should properly 

 be replaced by " biological pi ant -anatomy." Although the question at issue is 

 largely a matter of terminology, the author cannot assent to the change proposed. 

 if only because different authors employ the term " biology " in very different 

 senses. When used in its widest sense, biology includes the study of living organisms 

 in general ; sometimes, however, biology is defined as the study of the adaptations 

 of living organisms, while a certain number of investigators including the author 

 himself limit the scope of biology, by excluding adaptations other than those which 

 arise out of the relations of plants [or animals] to the various climatic and edaphic 

 factors of the environment, or to animals and other plants. At the present day, 

 biology in this limited sense is often termed " ecology." In the author's own opinion, 

 biological or ecological anatomy merely constitutes a special section of physiological 

 anatomy ; the study of function has always been regarded as the proper subject- 

 matter of physiology. 



Even in the first [German] edition of this book (p. 18) stress was laid upon the 

 fact that physiological plant-anatomy in the wide sense has two objects in view. 

 " On the one hand, it has to deal with the physiological processes that are respon- 

 sible for the internal structure of the plant-body, while, on the other, it is con- 

 stantly endeavouring to discover the relations between the structure and the function 

 of the various organs." In the second edition (p. 2) the former of these objects was 

 relegated to the science of ontogenetic or developmental anatomy (entiriclrlungs- 

 mechanische Anatomie), the latter being thus regarded as the sole aim of physiological 

 anatomy in the narrower sense. Berthold (Untersuchungen zur Physiologie der 

 pfianzlichen Organisation, Vol. II. Pt. I. p. 8 [1904]), therefore, in defining the 

 object of physiological anatomy as " the investigation of the mechanism of differen- 

 tiation during development and in the adult condition," is only endorsing the 

 author's own views. As a matter of fact, it is not quite evident how Berthold's 

 various special investigations, which are in themselves of the greatest interest, can 

 lead to an understanding of the " mechanism " of tissue-differentiation. This 

 question must, however, remain open, until the available data have been worked 

 up into a general theory. 



It is gratifying to note that in recent times those branches of physiological plant- 

 anatomy in the wide sense which concern themselves with the causes of differen- 

 tiation, are showing signs of active development. Vochting's " Untersuchungen zur 

 experimentellen Anatomie und Pathologie des Pflanzenkorpers " form a notable 

 contribution in this direction. The experimental aspect of Vochting's work cannot, 

 however, be regarded as its characteristic feature, since physiological anatomy, 

 in the narrow sense, is also largely based on experimental evidence. The author 



