812 



SCIENCE 



[N. S. Vol. XXXVI. No. 937 



ence of such a field. They then strike in 

 unison. "We may even suppose that there 

 exists a regulatory arrangement such that, 

 if some clocks are running slow and others 

 fast, the mechanism involved in striking 

 serves automatically to restore the clocks 

 to synchronous action. In this latter illus- 

 tration the striking of the clocks depends 

 in part upon their like construction. But 

 the action of an electro-magnetic field is 

 another and an essential factor in their con- 

 certed behavior. It is an agent entirely 

 outside of the clocks themselves which ex- 

 ercises a general control over their activi- 

 ties. 



In the first illustration of the clocks the 

 striking in unison consists, so far as we can 

 see at the moment, in the coincident acts of 

 ten absolutely independent and self-con- 

 tained mechanisms. In the second case 

 there is immediately present a specific co- 

 ordinating agent which compels the several 

 mechanisms to united and harmonious ac- 

 tion. In the absence of this agent the ten 

 clocks would not strike together — they 

 would not strike at all — nor would they 

 keep time together. Viewing such a group 

 of objects, we should see merely ten distinct 

 mechanisms lacking any coordination into 

 a unit or a whole. These illustrations hold 

 only if not examined below the surface. 

 Any inquiry as to how and why the clocks 

 came to be constructed as they are and, in 

 the first illustration, to be wound up, set 

 together, and so precisely regulated as to 

 keep time exactly together, will greatly 

 complicate matters and will render the ap- 

 propriateness of the illustration more or 

 less dubious. 



In this conception of organization as 

 being dependent upon an agent which exer- 

 cises general control over the elements 

 which are organized, we are not limited to 

 the idea that the control operates from 

 without the group of elements. In the case 



of the lens we may equally well imagine 

 that the controlling agent is in the lens 

 ectoderm itself; not, however, as embodied 

 in the separate mechanisms of the several 

 cells, but as something which transcends 

 cell mechanism, pervading, so to speak, the 

 whole region of lens ectoderm. Upon this 

 view a formative effect exerted by the optic 

 vesicle upon the lens may be supposed to 

 consist in a stimulus — merely a signal — 

 which serves to initiate the action of a lens- 

 determining agent in the superficial ecto- 

 derm. The development of a lens at places 

 other than where a lens normally develops 

 obviously presents difficulties to this hy- 

 pothesis. We may think of this internal 

 lens-determining agent as operating either 

 by effects upon the individual cells or by 

 action upon the ectodermal protoplasmic 

 sheet as a whole, regardless of cells. Whit- 

 man, in 1893, in his paper on "The Inade- 

 quacy of the Cell- Theory of Development"^ 

 gave us a vivid picture of living substance 

 developing into organic form through the 

 operation of large force complexes which 

 express themselves in thickenings, foldings, 

 and the great variety of form changes seen 

 in embryonic layers, irrespective of the 

 subdivision of these layers into cells. At 

 the present time there is a distinct tendency 

 away from any such broad and relatively 

 simple conception of developmental proc- 

 esses toward those which involve over- 

 whelming multiplicity of determining fac- 

 tors and indefinite minuteness of structural 

 mechanism. The current hypotheses which 

 have had their inception in the Mendelian 

 discovery and in correlated cytological re- 

 search tend toward exaltation of the im- 

 portance of the cell and more particularly 

 of the chromosome, if not of yet more mi- 

 nute and less accessible elements into which 

 the chromosome is hopefully to be shat- 

 tered. Yet I believe that the status of the 

 'Journal of Morphology, Vol. 8, pp. 639-658. 



