December 13, 1912] 



SCIENCE 



813 



chromosome is neither biologieally nor 

 philosophically so secure as to warrant us 

 in contemptuously rejecting any hypoth- 

 esis which fails to bow to the chromosome 

 as the omnipotent ruler of organic form. 



The first of our alternative views of or- 

 ganization attributes such harmonious and 

 concerted action as we frequently see 

 within a group of similar structural ele- 

 ments — for example, in a simple epithelium 

 consisting of numerous cells which are 

 structurally and functionally alike — to 

 homogeneity in that complex of factors, in- 

 ternal and external, which affects the sev- 

 eral members of the system, one factor be- 

 ing as essential as another, and no one factor 

 being especially responsible for the con- 

 certed action exhibited within the system. 

 If any one of these factors be removed, pro- 

 vided that it be not one which is directly 

 essential to the existence of the system, the 

 system immediately affected becomes no 

 less organized, but merely undergoes some 

 change in its organization. This change 

 may be one which interferes with the opera- 

 tion of some larger system and perhaps re- 

 sults in the downfall of the whole organ- 

 ism. In such a disaster we see the selective 

 action of "Nature" tending toward the 

 firmer establishment of harmoniously and 

 advantageously operating systems. A cer- 

 tain condition may be essential to the exist- 

 ence of a system, yet in no way responsible 

 for the peculiarities of that system. Oxy- 

 gen is essential to the existence of a dog, but 

 oxygen is not responsible for the fact that 

 certain living substance is organized as a 

 dog and not as a cat. 



In general, then, the first alternative as- 

 serts that organized form arises ontogenet- 

 ically, and is maintained, by the operation 

 of a multiplicity of factors which, for each 

 particular of that form, are coordinate in 

 rank and are associated together just as 

 they are, not by any immediately present 



and directly operative necessity, but only 

 indirectly through those several necessities 

 which have arisen from circumstances in 

 the past history of the genetic series. 

 When these factors are associated into a 

 homogeneous complex, the resulting type 

 of organization is such as we see in a 

 tissue whose numerous cells are alike in 

 histological differentiation. The shaping 

 of tissues into organs implies a precisely 

 corresponding departure from homogeneity 

 in the complex of factors concerned. The 

 modification or disappearance of any one 

 or several of these factors is not necessarily 

 followed by loss of organization, but only 

 by change in the relations which constitute 

 organization. 



The second alternative, while admitting 

 that organization must involve a multi- 

 plicity of factors, asserts that amongst these 

 is one factor, or a group of factors, of 

 dominant importance. This dominant fac- 

 tor may conceivably determine structural 

 uniformity and concerted action even when 

 the other factors affecting the system con- 

 stitute a complex which is not exactly 

 homogeneous. Upon the other hand, we 

 can imagine that the operation of a local- 

 ized dominant factor in a system other- 

 wise marked by perfect homogeneity of 

 conditions produces the differentiation of 

 a portion of that system into a system of 

 higher order, as when a region of a germ- 

 layer is modified into an embryonic organ. 

 With the removal of the dominant agent, 

 all other factors remaining the same, or- 

 ganization of a certain grade completely 

 disappears, although organizations of lower 

 order may remain. A ease which conceiv- 

 ably may prove to be an illustration of this 

 hypothesis is afforded by the headless frag- 

 ment of worm which, while remaining 

 alive for a considerable time, does not re- 

 generate. The living fragment exhibits 

 organizations of the various grades eorre- 



