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SCIENCE 



[N. S. Vol. XXVIII. No. 715 



To make these generalities concrete, take 

 the group of closely related, really in- 

 separable problems comprised under the 

 term distribution. I set for myself the 

 task of finding what species of salpa occur 

 in the area of the Pacific marked off for 

 study. After some years of collecting I 

 find a total of say eight species. By the 

 time my studies have been extensive 

 enough to make me nearly certain that no 

 others are to be found, I have become 

 keenly aware that some of these eight are 

 much more abundant than others. More- 

 over, by watching the tow-net hauls as they 

 come in from day to day and from week 

 to week, and by running back over my 

 records for some years, I make out, ap- 

 proximately at least, the order of abun- 

 dance of the different species for the area. 

 S. fiisiformis-runcinata clearly heads the 

 list, S. democratica-mucronata comes next, 

 then probably, though not quite certainly, 

 Cyclosalpa afflnis, and so on. Again, my 

 observations having reached over so long 

 a period and over so much material, I could 

 not fail to recognize certain rules accord- 

 ing to which some at least of the species, 

 i. e., the more abundant ones, are dis- 

 tributed through the year and through the 

 different depths of water. Intimations are 

 found too of rules prevailing in the repro- 

 ductive activity of the commoner species 

 for both the sexual and the asexual phases 

 of the life cycle. It seems that the dif- 

 ferent species reach their maximum abun- 

 dance at different times of the year; that 

 one species probably occurs at greater 

 depths than another ever does; that the 

 climax of abundance is brief for one 

 species while more extended for another, 

 and so on. 



Were I willing to stop with common- 

 places of zoology such as these, nothing 

 would be required for my pursuits beyond 

 efficient means of collecting (which in this 

 case happen to involve considerable ex- 



penditure), some diligence in getting to- 

 gether, examining and recording material, 

 and a little acumen in seeing and question- 

 asking. But surely the knowledge thus 

 gained is far from full knowledge of these 

 particular animals. How comes it that S. 

 fiisiformis-runcinata is the most abundant 

 species in these waters, while 8. cylindrica 

 turns up as hardly more than a straggler? 

 Why, as has been the case this summer 

 at least, does S. democratica-mucronata 

 swarm in early June when fiisiformis- 

 runcinata is comparatively rare, while the 

 latter species comes on by the millions in 

 late July, the former being at this time a 

 real rarity in the net hauls. 



Must I look to environment or the con- 

 stitution of the creatures, or to both for 

 answers? The very fact that I ask the 

 questions almost compels me to look to 

 both. If I knew for a certainty that the 

 full answer lay in either direction alone, 

 I should quite surely know the answer 

 itself, so should be under no necessity of 

 asking the questions. Well then, if my 

 questions are serious and I have gumption 

 enough to seek the answers where obviously 

 they must be sought, it will be necessary 

 to go at the constitution of the animals 

 more searchingly than before, and also at 

 the environment. In other words, I have 

 run with full force into the problem of 

 organic adaptation. There is no doubt in 

 my mind that much, if not the whole, of 

 the species problem, so overshadowing in 

 the biology of the last hundred or more 

 years, has been befogged by the generality 

 of idea and want of methodological ac- 

 curacy with which this very subject of 

 adaptation has been treated. Pinned 

 down to something really tangible and 

 definite, does not the question formulate it- 

 self in this way: In how far can the dif- 

 ferentials between two kinds of organism 

 ie correlated with differentials in the en- 

 vironments which they respectively oc- 



