540 



SCIENCE 



[Vol. LV, No. 1429 



ists to lose siglit of its peculiar advantages for 

 certain kinds of work. The lower angular 

 aperture obtainable with water contact as com- 

 pared with cedar oil, is compensated for in 

 several ways: first, it gives a longer working 

 distance, due to the necessarily narrower angle 

 of illumination,- — a very important thing in 

 high magnification. Second, it gives corre- 

 spondingly better penetration of the object ex- 

 amined. Third, there is the ease with which 

 both the slide (i. e., the object) and the ob- 

 jective are cleaned. A bit of blotting-paper 

 touched to the objective and the slide is all that 

 is necessary and the mount is ready for further 

 examination with lower magnification. But 

 with an oil-immersion the oil must be first re- 

 moved before a clear image can be had with 

 lower powers, and this takes time and skill. In 

 fact, if the mount is a temporary one and the 

 cover-glass not held in place by a cement ring 

 or hardened balsam, the cleaning is no job for 

 a careless man. Fourth, where the mount is in 

 water the water-immersion objective is free 

 from 'the annoying habit of dragging the cover- 

 glass over the specimen when the slide is 

 moved, — a fault of the oil-immersion due to 

 the greater viscosity of the oil connecting ob- 

 jective and cover-glass over that of the water 

 connecting cover-glass and slide. In freshly 

 studied marine mounts this is a big item. 

 Finally the lower cost of the water-immersion 

 objective is a factor well worth consideration. 

 It shonld be added, where oil contact between 

 substage condenser and slide is omittted, a very 

 frequent oversight with microscopists, the supe- 

 riority of resolution of an oil-immersion ob- 

 jective, due to its greater N. A., is lost and the 

 difllerence between it and a water-immersion 

 disappears. 



The only excuse for any immersion objective 

 is that very high magnification and resolution 

 are impracticable with di'y objectives because 

 of the working distance and the angle of illum- 

 ination involved. For this reason it seems to 

 me there is little excuse for immersion objec- 

 tives below the one twelfth inch English scale 

 or the 2 to 1.8 mm. standard scale. 



Albert Mann 

 C.4KNEGIE Institution, 

 Washington, D. C. 



QUOTATIONS 



HEALTH ORGANIZATION OF THE LEAGUE 

 OF NATIONS 

 An important branch of the work of the 

 League of Nations is that of its health organ- 

 ization. The International Health Conference 

 which was held in London in April, 1920, de- 

 clared that the epidemic situation was menacing 

 to all Europe, and that the task of fighting 

 epidemics was beyond the strength of voluntary 

 associations. The conference urged, therefore, 

 that the task should be entrusted to the League 

 of Nations as the only offieial international 

 organization with sufficient authority and 

 power to undertake the work. In accordance 

 with this recommendation an Epidemics Com- 

 mission was set up by tlie Council of the 

 League, and since the end of 1920 this commis- 

 sion has cooperated with the Polish health 

 authorities in their campaign against epidemics. 

 The commission, at the head of which was Dr. 

 Norman White, formerly sanitary commission- 

 er with the government of India, had complete 

 autonomy, but was responsible to the Council 

 of the League. The funds placed at its dis- 

 posal by the governments which are members 

 of the league were not large enough to make 

 possible an anti-epidemic campaign on the scale 

 originally planned, so the commission began 

 its work in Poland, and delivered to the Polish 

 health authorities the motor transport, soap, 

 clothing, medical stores, etc., most needed at 

 the outset of the campaign; it also pro\'ided 

 funds for the repair and equipment of bathing 

 and disinfecting establishments, quarantine sta- 

 tions, and hospitals, and gave fifty complete 

 fifty-bed hospital units. The work of this com- 

 mission was the first experiment in interna- 

 tional sanitary cooperation on a large scale, 

 and it has been a success. Last autumn, how- 

 ever, the epidemic situation in Russia, and the 

 consequent danger to her western neighbors, 

 became greatly aggravated on account of the 

 famine, and more drastic measures were found 

 necessary to deal with the situation. An all- 

 European anti-epidemic conference was there- 

 fore convened by Poland at Warsaw, with the 

 approval of the Council of the League of Na- 

 tions, and twenty-seven different nations took 

 part. It was notable as being the first general 



