April, '12] HUNTER: ROENTGEN RAYS 189 



this ant to the ultra-violet rays. Apparently, as an afterthought, 

 it was arranged to subject the insects to Roentgen rays. The appa- 

 ratus used was a box about the size of a cigar box in which the ant 

 colonies were placed. The apparatus was placed above the Roentgen 

 ray apparatus. Sliding lead plates on the l)ottom of the box allowed 

 the operators to direct the rays into different parts. When the ants 

 were collected in one corner, for instance, the rays were admitted 

 from directly beneath them. The results were absolutely negative. 

 The ants showed no tendency towards being affected and continued 

 their work in the normal manner. This was considered somewhat 

 remarkable by Professor Forel since it followed experiments which 

 had showed that the ants were quite sensitive to the ultra-violet rays. 

 As far as the Roentgen rays were concerned it was concluded that 

 they were not perceived by the ants. Neither was there any after- 

 effect upon the ants; they appeared entirely normal for a period of 

 eight days after the experiment, at which time the observations were 

 discontinued. 



The only other experiments of which we have been able to find any 

 record are dealt with in a paper by Professor Axenfelt in the Central- 

 blatt fiir Physiologic, 1897. In these experiments house flies were used. 

 The insects were placed in an apparatus consisting of two chambers 

 with a connecting passage. One of the chambers was constructed 

 of lead and the other of wood. Both could be completely darkened 

 at will. When the flies were in the leaden chamber, which, of course, 

 was not penetrated by the rays, an exposure of four or five minutes 

 caused them to pass over to the other chamber. When they were 

 placed in the wooden chamber and exposed to the rays they remained 

 there even when that chamber was darkened and the other light. 

 The investigator concluded that the experiments showed that the 

 house fly can perceive Roentgen rays and that they affect it in much 

 the same way as ordinary light. The account of the experiments 

 which was published is not detailed and it seems that the conclusions 

 the author reached are hardly above criticism. There is a possibility 

 that a chfference in temperature in the two chambers due to the con- 

 struction of different materials may have caused the movement of 

 the insects from one to the other. This supposition appears to be 

 more plausible in view of the experiments of Forel and Dnfour which 

 were -performed under the most careful conditions of control. 



One of the many remarkable features of Roentgen rays is their 

 effect upon the sexual organs of certain animals including man. Until 

 it was discovered, some ten years ago, that the rays had a very remark- 

 able effect upon the organs of regeneration even when no external 

 lesions whatever are caused, many operators were completely ster- 



