Non-Sterilising doses of radiation which cause no demonstrable deleterious effect on the health of the individual may, nevertheless, cause serious changes in the chromosomes of the spermatozoa or ova, resulting in manifest disability of various types in subsequent generations. The writer first became interested in this subject because of requests that he should give non-sterilising doses of radiation to non-fertile women, and to women with dysmenorrhœa. The extent to which one should be prepared to mortgage the future of the race for the benefit of any one patient may be a matter of opinion, but it is desirable that before doing so one should have a true appreciation so difficult that, for the purposes of a Ministry of Labour Panel on Occupational Effects of Radiation, he wrote to various authorities for their views on the subject and subsequently arranged a meeting at which the matter was thoroughly discussed. Those present at the meeting were: Dr. D. G. Catcheside, University of Cambridge; Professor F. ...