SHULL: GENETICS 127 



With the rise of recorded science came also authoritarianism, — the estab- 

 Hshment of "schools" consisting of the students and followers of individual 

 observers, thinkers and teachers. Such groups of disciples did not as a rule 

 become independent observers, nor independent thinkers. Rather were they 

 simple protagonists of the theories of their leaders and disputatious opponents 

 of the divergent views of other leaders. 



Not until the coming of the Renaissance, and the development of the 

 printing-press, cheapening and making more effective the process of per- 

 manent record and of intercommunication, could there be the accumulation of 

 the observations and of philosophical concepts and theories of many indi- 

 viduals which gradually built up the diversification of knowledge which char- 

 acterizes the field of science as we know it today. Along with this accumulation 

 of recorded fact and theory, arose the competitive spirit, the checking and re- 

 checking of hypotheses by new observation, the winnowing of truth from the 

 chaff of fallacy. 



The scientific field has been enlarged by bringing new objects under ob- 

 servation, through exploration and importation of materials from geo- 

 graphical areas of ever increasing extent. Also the invention of new instru- 

 ments of research — the microscope, microtome, centrifuge, galvanometer, po- 

 tentiometer, Crooks tube, cyclotron, electron microscope, — and the discovery 

 of new effective chemicals, such as indole acetic acid, thiamin, colchicine, etc., 

 have made possible new analyses and the perception of new relationships not 

 previously recognized. Similar expansion has come from the discovery of 

 exceptionally favorable research organisms and structures, as, for example, 

 the mutation phenomena, the chromosome circles, and lethal factors of 

 Oenothera; the regenerative capacity and tolerance of transplantation in Am- 

 phibians; the almost limitless genetical and cytological advantages of Dro- 

 sophila for studies on the relations between genes and chromosomes ; the effec- 

 tiveness of the coleoptiles of Avena for the recognition of growth-promoting 

 substances ; and many others. All of these have brought about so great an 

 expansion of the field of biological science that ever closer specialization is re- 

 quired in order to make further progress. This situation has been long recog- 

 nized and jokingly referred to as "learning more and more about less and 

 less." 



So much for the expansion and diversification of biological science. As a 

 result the science of biology has been divided into a very large number of 

 separate branches, now commonly referred to as the plant sciences and the 

 animal sciences, plus those which relate about equally to both plants and 

 animals, such as general or cellular biology, ecology, and genetics. 



The specialists working in each of these biological fields have found it 

 advantageous to organize special societies for the holding of periodical meet- 



