THE GROWTH OF GROUPS 161 



Lugaro, the author of " Modern Problems in Psy- 

 chiatry," closes his introduction to the subject in the 

 following words : " From this rapid summary we see that 

 Psychiatry not only enters into intimate contact with 

 all the fundamental sciences of medicine and biology in 

 general, but also touches upon the social and moral 

 sciences. On all it imposes problems, from all it requests 

 data. And rarely are these sciences sufficiently advanced 

 to solve those problems or to supply those data. There 

 is no doubt that all sciences have a reciprocal connection 

 and each advances by taking advantage of the progress 

 made by others." 



In recognizing the characters of living things and the 

 manner of their origin, biology has made permanent 

 progress. We are beginning to recognize that all estab- 

 lished and widespread groups, such as are called species 

 in a wide sense, appear polymorphic when examined 

 closely enough. They are not one kind, strictly speaking, 

 but a mixture of kinds. The several mutants of (Enothera 

 which form the basis of De Vries' enlightening work 

 would be classed by an unobservant person as one kind 

 under the name of evening primrose. De Vries regarded 

 the events witnessed in (Enothera as special to that group 

 because it was in a mutating period, but there is reason 

 to believe that many other widespread groups of organisms 

 will be found to be in a similar state, if examined widely 

 and closely. It seems that the potato-beetles of America 

 and the house-rats of India are in a similar state. 



Let us forget for a moment the various conceptions 

 indicated by the words species, variety, character, etc., 

 and describe De Vries' great experiment in general terms. 

 He took a kind of organism (Enothera lamarckiana and 



