June 30, 1911] 



SCIENCE 



1001 



Mr. Raymond Binford, Jolms Hopkins 

 University, continued the study of the life 

 histories of the crabs of Beaufort, especially 

 that of Menippe mercenaria. By a later 

 study of the material killed and preserved 

 during the summer, the processes of fertiliza- 

 tion and gastrulation in this crab are being 

 worked out. 



In experiments in which eggs were sub- 

 jected to differences of temperature, those 

 which were kept a few degrees above normal 

 hatched nine days after they were fertilized, 

 while those kept below the normal hatched on 

 the thirteenth day after fertilization. 



Some twelve hundred of these crabs were 

 caught in the waters about the Beaufort 

 harbor during the summer. 



Mr. J. D. Ives, instructor in biology, Wake 

 Forest College, made observations on the re- 

 generation of nemerteans and Amphitrite 

 during the month of August. Sections of 

 nemerteans were found to regenerate read- 

 ily. The anterior surfaces of the sections 

 were found to regenerate but a small amount 

 of new material compared with that formed by 

 the posterior surfaces. The posterior surfaces 

 of the sections regenerated rapidly. In about 

 four weeks, sections of worms not over one 

 half inch long were found to more than 

 double their length with new material. 



The tentacles of Amphitrite when pulled 

 off were foilnd to regenerate readily. In 

 about ten days or two weeks after removal, 

 the tentacles attained nearly an inch or about 

 half of their normal length. When the en- 

 tire tentacle bearing somite is cut off, the 

 worm lives almost as well as when only the 

 tentacles are removed. When the somites 

 bearing both the tentacles and the first pair 

 of branchiae were cut off, some few specimens 

 lived for over two weeks. 



Henry D. Aller 



TBE BIOLOGICAL EFFECTS OF EADIUM^ 

 Among the first discoveries made after the 



production of concentrated radium salts was 



that radium is capable of causing intense ef- 

 ' Address before the Illinois State Academy of 



Science, Chicago, February 18, 1911. 



fects upon living tissues. We were not un- 

 prepared for such a discovery in the case of 

 radium because similar phenomena had been 

 observed early in the study of X-rays. In the 

 case of X-rays the discovery had been totally, 

 and very unfortunately, unexpected. The 

 early burns from radium were of the same 

 character as X-ray burns, and later detailed 

 study has shown that the effects upon tissues 

 of the two agents are practically identical. An 

 appreciation of this fact is useful at the outset 

 of a consideration of the biological effects of 

 radium; it gives one at once a large number 

 of analogous facts that have been well studied 

 and, because of the more extensive study that 

 has been made of the biological effects of X- 

 rays, enables one to correlate more satisfac- 

 torily some of the isolated observations upon 

 the actions of radium. Because the gross ef- 

 fects of radium, which furnish us many val- 

 uable facts, can be studed in the skin, and be- 

 cause the effects upon the various tissues of 

 the skin give us the most comprehensive view 

 of the biological effects in general of radium, 

 it is conducive to clearness to consider first 

 the effects of radium upon the skin, meaning 

 by the skin in this connection the human skin 

 or skin of similar structure of other animals. 

 When the human skin is exposed for a suffi- 

 cient length of time to an active radium salt 

 a peculiar and definite reaction is set up, of 

 which the first striking feature is that it does 

 not develop until after a relatively long 

 period of quiescence — as a rule about two 

 weeks. In a skin containing a considerable 

 amount of pigment, there is first an increase 

 of pigment, shown by an ordinary " tanning " 

 of the exposed surfaces. If there are any 

 freckles or pigmented spots in the exposed 

 area, these become darker. Along with 

 this pigment stimulation there occurs a 

 reddening of the skin, with a feeling of 

 irritation and burning such as one has 

 from sunburn. The reaction may stop at 

 this point and after a few days gradually sub- 

 side ; the redness and irritation diminish, there 

 is some scaling from the surface and in a few 

 days more no evidence of the reaction remains, 



