396 



SCIENCE 



[N. S. Vol. XLIV. No. 1133 



in which M is a substance which determines 

 the rate of penetration of salts and the elec- 

 trical resistance of the protoplasm. 



If the antagonistic substances are ISTaCl and 

 CaCh it appears that CaCL, accelerates the re- 

 action A — > M while both A — > M and M -> B 

 are inhibited by a salt compound formed by 

 the union of EaCl and CaCl 2 with a constit- 

 uent of the protoplasm. 



Prom this standpoint the slow penetration 

 of antagonistic substances should not have un- 

 favorable results provided these substances are 

 properly balanced at the start and remain so 

 (i. e., if their relative proportions are not too 

 much changed by unequal speed of diffusion, 

 precipitation, chemical union, etc.) after they 

 enter the cell. For they must affect the life 

 processes mentioned above in quite the same 

 way in the interior of the cell as at the sur- 

 face 7 and these life processes will go on in the 

 normal way so long as the antagonistic sub- 

 stances within the cell remain properly bal- 

 anced. 



The result will be the preservation of nor- 

 mal permeability as well as of all other prop- 

 erties essential to life. 



It has been shown by the writer 8 that the 

 normal permeability may be regarded as a 

 sensitive and accurate indicator of health and 

 vitality. All factors which disturb it bring 

 about temporary or permanent injury and 

 eventually produce death if the action be suffi- 

 ciently prolonged. It is therefore evident that 

 the life processes which preserve normal per- 

 meability are of peculiar importance and that 

 the manner in which they are influenced by 

 antagonistic substances is of especial interest. 

 Methods are being developed for the study of 

 these questions and it appears probable that a 

 considerable amount of information can be ob- 

 tained in regard to the nature of these proc- 

 esses. 



Summary. — Antagonism has been explained 



7 Whatever effects are found at the outer sur- 

 face of the cell are doubtless to be found also at 

 many of the internal surfaces such as the sur- 

 faces of vacuoles, plastids, microsomes, etc. 



s Plant World, 16, 143, 1913. Science, N. S., 

 40, 488, 1914. 



by assuming that antagonistic substances pre- 

 vent each other from entering the cell. A 

 difficulty is found in the fact that they slowly 

 penetrate the cell even in a properly balanced 

 solution. This difficulty disappears if we sup- 

 pose that the antagonistic substances affect 

 certain life processes which control permea- 

 bility. So long as they are present in the 

 right proportions their effect on these proc- 

 esses is favorable and their penetration into 

 the cell can do no harm. 



The preservation of normal permeability 

 may therefore be regarded as the result rather 

 than as the cause of antagonism. 



w. j. v. osterhout 



Laboratory of Plant Physiology, 

 Harvard University 



the determination of relative humidity 



In the present stage of knowledge of what 

 constitutes healthful and comfortable air for 

 the average healthy person, the question of 

 the value and significance of the determination 

 of relative humidity is still decidedly debata- 

 ble. It will, therefore, be necessary to continue 

 such determinations in connection with other 

 types of ventilation tests, in order to assign 

 to relative humidity its proper value as a factor 

 in the problem of conditioning air for health 

 and comfort. There is at least one standard 

 procedure for this determination — the use of 

 the sling psychrometer. This instrument is 

 supposed to give reliable results if used in ac- 

 cordance with the government directions. One 

 need not spend the fancy price for the instru- 

 ment de luxe. Two thermometers, firmly lashed 

 together in such a way that the bulb of one 

 projects beyond that of the other gives perfect 

 satisfaction. The lower bulb is moistened in 

 the usual way and the pair is swung by a 

 strong cord. 



This method has obvious limitations. It 

 can not be used under many circumstances 

 where the determination of relative humidity 

 is desired, e. g., in crowded places, between 

 skin and clothing, etc. It is ofttimes incon- 

 venient and dangerous to use, e. g., in con- 

 spicuous places such as churches and libraries, 

 and in cramped quarters such as the berths of 



