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SCIENCE. 



[N. S. Vol. XX. No. 515. 



variable nature of an organ that may arise 

 from a given primordium. When pri- 

 mbrdia that usually develop mierospo- 

 rangiate organs produce megasporangiate 

 ones, or vice versa; when the same plant 

 body produces sporangia or gametangia 

 in response to conditions imposed by the 

 experimenter; it becomes evident that 

 primordia may be indifferent not only as 

 to form, but also as to nature. 



This meant a general unsettling of mor- 

 phological conceptions. To find, for ex- 

 ample, that a given cell is not set apart 

 from its first appearance to function as an 

 archesporial cell, but that there are as 

 many potential archesporial cells as there 

 are cells in an extensive tissue; and fur- 

 ther to find that the archesporial cell when 

 discovered by its functioning does not 

 necessarily produce all the sporogenous 

 tissue, is to abandon the idea of predestina- 

 tion and of defining structures on a rigid 

 moi-phological basis. 



3. The Origin of Species. — Probably the 

 greatest triumph of experimental morphol- 

 ogy thus far is that it has put the problem 

 of the origin of species upon an experi- 

 mental basis. The ability to vary, and to 

 varj'- promptly and widely, when consid- 

 ered in connection with structures used by 

 taxonomists, means new species under cer- 

 tain conditions. To analyze these condi- 

 tions is a problem of enormous complexity, 

 but to have the problem clearly before us 

 is but the prelude to its solution. There is 

 still a tendency to call things inherent that 

 are not apparent, but this is a habit not 

 easily outgrown, and such a problem as the 

 origin of species will long have its con- 

 venient category of 'inherent tendencies.' 



Certain conclusions are inevitable as one 

 considers the perspective opened by ex- 

 perimental morphology. 



In the first place, it would seem that 

 what we have called 'biological laws' are 

 also the laws of physics and chemistry, 



and the experimenter must be prepared to 

 use all the refinements of method devel- 

 oped by physicists and chemists. Much of 

 the work done in the name of experimental 

 morphology is as yet crude in the extreme, 

 and we are often left with a confusing 

 plexus of conditions rather than with a 

 satisfactory analysis. To grow plants, to 

 observe certain results and to draw con- 

 clusions, too frequently means the arbitrary 

 or ignorant choice of one factor out of a 

 possible score to be found in the uncon- 

 trolled conditions. 



In the second place, that phase of ecology 

 which deals with what are called 'adapta- 

 tions to environment ' simply catalogues the 

 materials of experimental morphology and 

 must be merged with it. To retain it as a 

 distinct field of work is to doom it to steril- 

 ity, for it can only bear fruit as it becomes 

 an experimental subject, and then it is ex- 

 perimental morphology. 



In the third place, experimental morphol- 

 ogy, with its background of physics and 

 chemistry, is more closely related to physi- 

 ology than it is to the older phases of 

 morphology; which leads to the conclusion 

 that the fundamental problems of mor- 

 phology are physiological. We may look 

 at the situation from either standpoint, and 

 say that the most recent phase of morphol- 

 ogy entrenches upon physiology, or that 

 the boundaries of physiology must be ex- 

 tended enough to include morphology. 

 To-day the two subjects axe handicapped; 

 for morphologists are not physiologists 

 enough to know how to handle and inter- 

 pret their material, and physiologists are 

 not morphologists enough to know the ex- 

 tent and significance of their material. The 

 training of the future must not differen- 

 tiate these two subjects still further, but 

 must combine them for effective results. 



This modern tendency to cross old-estab- 

 lished boundaries between subjects is evi- 



