IfrQ The Philippine Journal of Science ms 



tion, it is genetically associated with the scope of our idea of 

 a species; and approaching the subject from this point, I may 

 come again into agreement with Doctor Willis, and this time 

 on his own ground. There is a constant tendency among both 

 botanists and zoologists to place an ever finer construction on the 

 idea of a species. Each decade sees the recognition as species 

 of many groups of plants which previously were combined with 

 other groups, either as varieties or without even varietal dis- 

 tinction. In some cases, this change is due to more careful in- 

 vestigation of resemblances and differences, but frequently it 

 is merely the expression of a change in attitude as to what a 

 single species should include. The extreme in this direction 

 was reached years ago by Jordan, in the recognition of what are 

 commonly referred to as Jordanian, in distinction to Linnaean, 

 species. As a matter of fact, no botanist of to-day holds himself 

 to the Linnaean idea. If the present tendency continues un- 

 checked, our descendants will all find themselves following 

 Jordan's policy. In practice, I do not expect the tendency to 

 extend so far. Such a practice applied to all plants would make 

 systematic botany a subject inconveniently vast and cumbersome, 

 even for the larger number of botanists that may be expected 

 in future years. In the case of the very great majority of plants, 

 the recognition of Jordanian species, supposing that they exist, 

 would serve no useful purpose. In the case of such plants as 

 rice, and other plants of great industrial importance, it will be 

 worth while, and will surely be done, whatever the nomenclato- 

 rial rank the forms may be given. 



Our nomenclatorial divisions— families, genera, species, and 

 varieties or forms — are, as I have repeatedly pointed out, in 

 part functions of the diagnostic peculiarities of plants, and in 

 part functions of our convenience. The old idea, that a species 

 is a group of plants distinct from any other group, in the sense 

 that we know no practically continuous series which connects it 

 or has connected it with any other group, was never anything 

 but an expression of contemporary ignorance, and is as dead 

 to-day as the idea that the species were separate manifestations 

 of the Creator's activity. This is as true of genera and families 

 as it is of species. "We would still want to recognize genera 

 and species, if the tree of life could be reproduced in every 

 detail." 5 



As we fill in our skeleton structure of the tree of life, it is 

 convenience that must determine what genera, species, and other 



5 Philip. Joum. Sci. 8 (1913) Bot. 153. 



