384 Action of the Genetic Material 



are found. (One of them, flower color, will be mentioned below.) 

 A less satisfactory case will be expected in monosomies, trisomies, 

 and so on, in which a background of disturbed "genie balance" is 

 involved. We saw in the discussion of Stern's work (and the same 

 applies to the extensive work with other loci) that mutant loci in 

 Drosophilas fourth chromosome in the chromosomal dosages of haplo-, 

 diplo-, triplo-IV give regular effects in relation to dosage, though the 

 possibility could not be excluded that in some of the irregular results 

 that feature may be involved. The most extensive data available other- 

 wise for different extra chromosomes are contained in Blakeslee's 

 famous work on Datura. However, here no individual loci were 

 studied, and the general differences found cannot be attributed simply 

 to dosage differences of loci, and therefore cannot be used for an 

 analysis of genie action. 



D. GENIC ACTION IN FOUR DIMENSIONS 



The greatest difficulty in the study of genie actions in controlling 

 development is met with when we try to visualize how they are inter- 

 locked in order to produce their effects locally, that is, in the three 

 dimensions of space and in the fourth dimension of time, at a given 

 moment. To understand normal development in terms of genie action 

 we must integrate all the individual sources of information on the 

 action of mutant loci and infer the action of the normal genie material. 

 In doing so it should not make any difference what views we hold on 

 the nature of the genie material — the classic gene concept or the 

 modern pattern idea. In any case the information we have is derived 

 almost exclusively from the results of interference of mutant loci with 

 the normal course of development (and the analysis of the factors of 

 development by experimental embryology). Therefore, whatever the 

 constitution of the normal genie material, it must act in the way 

 revealed by mutant interference with its action. The general picture 

 of genie control of orderly (i.e., four-dimensional) development, has 

 been given in the foregoing discussions of individual phases of the 

 process, and some integration of the diverse actions has been pre- 

 sented, wherever there was a need of it. But no attempt was made to 

 offer a complete picture of the interplay of all development-control- 

 ling reactions, nor were all groups of facts presented which should 

 enter such an integration. Thus, in trying to visualize the integrated 

 action of the genie material we shall have to add some more relevant 

 factual material. 



If we are not dogmatic, we might expect most of the interpreta- 



