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THE AMEBIC AN NATURALIST [Vol. XLIII 



and all with phylogenetic relations in view. This has 

 meant comparison at every step; and as a conse- 

 quence, there is available to-day a wealth of important 

 information such as we have never possessed before. 

 The process of sifting has gone along with the work of 

 accumulation, so that our facts are sorted, and in shape 

 to use. We may not use all this material, but whatever 

 has been collected with a phylogenetic purpose must be 

 reckoned with. One interesting result from this wealth 

 of material has been the loosening up of all our concep- 

 tions of structures. No definitions have stood; and our 

 statements to elementary classes are all with important 

 mental reservations. This substitution of a general 

 situation for a rigid definition is also a substitution of 

 knowledge for terminology, and introduces into our 

 phylogenetic schemes a conception of variation that 

 makes them workable. 



So many definite lines of attack have resulted in still 

 more numerous schemes of phylogeny. Each investi- 

 gator naturally regards his own field of work as phylo- 

 genetically the important one, otherwise he would not 

 be working in it. A detailed examination, however, of 

 all the schemes based upon extensive investigation re- 

 veals the fact that the differences have to do in the main 

 with subordinate features. Certain large conclusions 

 may be regarded as fairly well established, so far as our 

 present information goes. Some of them I may venture 

 to mention, for they represent fairly well the progress 

 of a decade. Of course the progress of largest im- 

 portance is the fact that so much trained investigation 

 is being directed along so many convergent lines that 

 meet in the problem of phylogeny. Never was morphol- 

 ogy so well equipped as it is now. The large results to 

 be mentioned are those concerning which there is sub- 

 stantial agreement; which means results that must have 

 stood the test of morphology, anatomy and history. 



Discredit has been thrown upon the cell-by-cell studies 

 of such structures as the embryo, gametophytes, sex or- 



