408 EFFECT OF INFRA RED 



After the nemas had been rayed and returned to water in a watch- 

 glass, and after they had resumed their former less active somewhat 

 outstretched state, they were tested again and again with the infra- 

 red rays. Two observers, noting the nemas before they were removed 

 from the watchglass of water and after they had been rayed, declared the 

 ovijection to be stimulated, and in one case the stimulation to be very 

 marked indeed. In this case, at the time when the nema was removed 

 from the glass, oviposition was diminishing to almost nil, only now and 

 then an egg being deposited, at intervals of half a minute or there- 

 abouts; however, after she had been rayed and returned to the water 

 where her behavior could be observed more accurately, deposition 

 was going on vigorously, batches of something like twenty eggs were 

 being ejected at intervals of five to ten seconds. It should be re- 

 membered that these two females already had their egg-laying capacity 

 partially exhausted and were therefore probably less favorable speci- 

 mens for experiment than if they had just issued from the ground. 



The conclusions drawn from the experiments were that, without 

 doubt, the radiant heat from the hot steel met with instant response by the 

 nema and that the response was very definite and that the egg deposition 

 was very markedly stimulated by the rays.* 



Apart from ultra-violet, apparently very little is known about the 

 relative amounts of various light frequencies that are passed through 

 different quantities of fog and watery vapor in the atmosphere. It is 

 known that fog and vapor are more or less impervious to ultra-violet, 

 but pervious to many other frequencies, among them blue and a cer- 

 tain amount of red and infra-red. However, nobody appears to have 

 devised a method or instrument by which the amount of any particular 

 one of these various other frequencies penetrating under various atmos- 

 pheric conditions can be satisfactorily measured, although there is 

 reason to hope that such data can be established. 



It is very evident, however, that during the morning under con- 

 sideration, which was showery with light rain much of the time, the 

 weather varying all the way from thick fog to almost sunny, fog so 

 thick that the fog-horns were blowing, and yet at times the sky toward 

 the east such that the sunlight came through rather clearly , it is 

 very evident that the amount of any given spectrum frequency reach- 

 ing the experiment field probably would vary during the morning 

 nearly through the entire daylight scale, or at least much of it. 



* But whatever stimulus, if any, the nema received from the sky was not sufficient 

 by itself to cause any marked oviposition. 



