January 17, 1908] 



SCIENCE 



99 



material in egg and sperm. So far as those 

 characteristics are concerned which appear 

 late in development, it is highly probable 

 that there is equality of inheritance from 

 both parents, but in the early and main 

 features of development, hereditary traits, 

 as well as material substance, are derived 

 chiefly from the mother. 



Finally I may call attention briefly to 

 the bearing of these conclusions on the 

 mechanism of evolution. I have elsewhere 

 (Science, No. 536) discussed the proposi- 

 tion that the evolution of organisms must 

 take place through the evolution of their 

 germ cells, and that relatively slight modi- 

 fications in the localization of the forma- 

 tive substances of the egg may produce 

 profound modifications in the adult. 



One of the principal difficulties in explaining, 

 on evolutionary grounds, the origin of different 

 phyla has been the dissimilar locations of corre- 

 sponding organs or parts. These difficulties are 

 well illustrated by the theories wliich attempt to 

 derive the vertebrates from the annelids or from 

 any other invertebrate type. If evolution takes 

 place through the transformation of the egg cell 

 rather than of the adult, it is no more difficult 

 to explain the different locations of corresponding 

 parts in these phyla than their different qualities. 

 Changes in the relative positions of parts which 

 would be absolutely impossible in the adult may 

 be readily accomplished in the unsegmented egg, 

 as is shown by cases of inverse symmetry. 



In the light of the conclusion that only 

 the later and more detailed differentiations 

 are influenced by the sperm, it follows that 

 experimental work which aims to modify 

 the fundamental features of an organism 

 must be directed to the ovarian egg rather 

 than to the sperm, or to the developing 

 embryo. Edwin Gr. Conklin 



University of Pennsylvania 



THE INFLUENCE OF FRICTION IN 



ECONOMICS 1 



. Theee has always prevailed, since the 

 foundation of systematic political economy, 

 " Address of the vice-president and chairman of 

 Section I — Economics and Social Science — ^Amer- 

 ican Association for the Advancement of Science, 

 Chicago meeting, 1907-8. 



a conflict between men of theory and men 

 of action. Men engaged in practical busi- 

 ness affairs and even in great financial 

 operations have refused again and again to 

 accept the abstract conclusions drawn from 

 so-called economic laws, and have insisted 

 that the rule of practical common sense, 

 if based upon a careful observation of 

 facts, was a safer guide than economic 

 theory. In the field of tariff legislation 

 this divergence of opinion has perhaps 

 been more marked than in the field of 

 finance. This difference, so far as it 

 exists, tends to support the view which is 

 here laid down— that the economist has 

 erred in a measure in seeking to apply 

 abstract principles too rigidly to actual 

 conditions by failing to take account of 

 friction in the application of these prin- 

 ciples. 



The economist, working out the theory 

 of the conduct of the economic man ac- 

 cording to the principles of enlightened 

 self-interest, finds in them a harmony and 

 a rule of law which in his mind give them 

 something of the beauty and precision of 

 the movement of the spheres. He is im- 

 patient of qualifications which detract from 

 the simple and direct operation of the prin- 

 ciples derived from these theories. The 

 principles of the flow of capital to the 

 market where the price paid for its use is 

 the highest, of changes in prices according 

 to changes in the quantity of money, of the 

 evolution of production and manufactures 

 in such a manner that each community and 

 each individual shall flnd his most profit- 

 able work under the reg'ime of free com- 

 petition, are principles so simple to his 

 mind that he can not understand how they 

 can be disputed. 



Nor could such principles be long dis- 

 puted, if the current of trade flowed as 

 freely as the waters of the ocean into a 

 vacuum wherever scarcity indicated a 

 given demand, and if money and capital 



