Probable Future of Aiixinology 825 



short, progress until it resembles in its mode of operation the sciences 

 of biochemistry and of biophysics today. So this is another trend. 



We know, too, that because there is such a thing as auxin, one 

 might well look for other kinds of growth factors. That there are 

 other kinds of growth factors is now amply attested by the fact that 

 we know about some of them. We know about gibberellin, for ex- 

 ample, and therefore all of the kinds of questions that have been 

 asked about auxin can now be asked about gibberellin, too. When all 

 of the problems of auxinology are solved, it will not mean that we 

 have nothing to do. We can always convert ourselves to working on 

 gibberellin, or working on the isolation of flowering hormone, or 

 some other lesser known growth factor. There is an old saying, or if 

 there isn't such an old saying, there ought to be one, that "Old auxin- 

 ologists never die, they turn into gibberellinologists." So there are 

 many things to do in the study of plant growth factors other than 

 auxin itself. I predict, therefore, that within another 25 years certain- 

 ly, the chemical nature and mode of action of a vast array of further 

 plant hormones will be understood. 



What, now, is going to happen after plant physiologists have got- 

 ten busy and found out about the nature of all of these other growth 

 factors and know how all of them do their work? What will people 

 do then? I have a suggestion. It seems to me that really the most 

 basic biological problem that confronts us, now that the problem of 

 the nature of genetic information and its replication has been wound 

 up, is the problem of differentiation. We have mentioned differentia- 

 tion many times during the course of this conference. No one has 

 explained anything about differentiation; we just say to each other, 

 "Oh, that's differentiation," or "This substance influences differentia- 

 tion," or something of similar ilk. We fail to understand differentia- 

 tion because we haven't yet really had a tool which would enable us to 

 approach the subject in a productive experimental way. How does 

 differentiation take place? It is my prediction that another generation 

 from now this may well be one of the principal studies to which people 

 who would have been auxinologists in the olden days will turn their 

 talents. And I have a little suggestion, too, about how the approach 

 to the study of differentiation might possibly be made. I want to 

 make this suggestion now because perhaps some of us can be thinking 

 about it and perhaps we can jump the gun a little and get on with 

 the study of differentiation. 



It is implicit in the thinking of every biologist and has been im- 

 plicit, too, to a small extent in our discussion at these meetings, that 

 when cells of common cell ancestry differentiate along different path- 

 ways and turn into different kinds of cells, these different kinds of 



