Varietäten etc. — Physiologie. 227 



groundproblems ot evolution. First, distinction is made between the 

 origins of numerical and of proportional characters, their use in 

 Classification of mammals is discussed; next the observations of a 

 field zoologist on the modes of origin of numerical and proportional 

 characters are spoken of; a critical examination of likeness and 

 unlikeness between paleontologic and Zoologie observations follows; 

 differences of opinion as to the origin of new numerical and pro- 

 portional characters are criticised; the observed differences in the 

 origin and inheritance of proportional and numerical characters; 

 the significance of Waage n's observations on the continuous and 

 orthogenic origin of new characters, as also that ot de Vries' 

 work on the discontinuous and indefinite origin of characters is 

 pointed out. 



The last part of the paper, consisting of the chapters: Separa- 

 biiity of characters in the body; Separability of characters in the 

 germ; Conception of the „Least Character"; „Least characters" in 

 Classification and systematic work; Theoretical conclusions as to 

 „Characters" and the „Organism"; are for the botanist mostly inte- 

 resting, especially his conception of „least characters", that are 

 defined by an enumeration of their known properties: „As distin- 

 guished from a group of characters the properties of a „character" 

 are its separabilit}^ its independence, its individuality, its own 

 rate of movement ontogenetic and phyletic, its differentiation by 

 these properties from other least characters. Its separability in 

 heredity is shown where it can be hybridized." 



In this manner results the conception of an individual as a 

 colony of „characters" each with its principles of independence and 

 its principles of correlation, germinal in origin but subject to soma- 

 tic modification by environment and habit. 



The Observation of „characters" in phyla or groups of organisms 

 advancing on a grand scale in space or in time shows that the 

 Darwinian tradition of the origin of „species" from fortuitous sal- 

 tatory characters is so partial and inadequate as to be practically 

 false. „It has been observed that every organism consists of an almost 

 infinite number of characters, it has also been observed that the 

 evolution of some of these characters may be so conspicuous as for 

 a time to attract the attention of the observer or as to constitute 

 the Chief magnete for the power of selection. It has not been observed 

 that the entire organism waits on any orie of these characters. On 

 the contrary, in all progressive organisms in which a very large 

 number of characters are simultaneously observed it proves that 

 every character in every part of the body is in a continuous State 

 of movement". „Selection is operating always upon the sum of all 

 the movements, actions and reactions of characters known as the 

 Organism and upon all Single characters of survival or elimination 

 value". 



„Paleontology affords only indirect evidence as to germinal 

 „factors" but it offers the most positive testimony both as to evo- 

 lution largely by the loss of characters, as in the case of the family 

 of horses, and evolution largely by the addition of characters, as in 



the family of titanotheres [Eotitanops > Broirtothenu'my\ 



M. J. Sirks (Wageningen). 



Hempel, J., Bidrag til Kundskaben om Succulenternes Fy 

 siologi. [Beiträge zur Kenntniss der Physiologie der Sitccu 



