22 



SCIENCE 



[Vol. LV. No. 1410. 



It appears that some arrangement whereby 

 power companies supplying large cities could 

 have recourse to observations of daylight 

 illumination, especially during the thunder- 

 storm season, would be of decided benefit to 

 them, for the falling ofE of this illumination 

 would afford an index as to the proper time to 

 prepare to supply additional current. 



This sketch is sufficient to indicate the char- 

 acter of the important work being done by 

 Dr. Kimball and to suggest some of the indus- 

 trial benefits to be derived from the study of 

 daylight undei' various tj'pes of cloudy and 

 smoky sky. 



C. Le Rot Meisixgee 

 Washington, D. C. 



ON STEREOTROPISM AS A CAUSE OF CELL 



DEGENERATION AND DEATH, AND ON 



MEANS TO PROLONG THE LIFE 



OF CELLS 



In former investigations we have shown i- ^ 

 that amoebocytes of Limulus have the tendency 

 to move and to spread out in contact with 

 solid bodies. We thus found another instance 

 of a reaction which is common to many kinds 

 of cells and which we observed and analyzed 

 in 1897 and subsequent years and which we 

 designated as stereotropism of tissue cells ^. 



We further found that the blood cells of 

 Limulus, as a result of this stereotropic re- 

 sponse and the concomitant spreading out of 

 their protoplasm along the sui'faee of the 

 solid body, underwent degenerative changes; 

 the}' lost their granules, became hyaline and 

 gradually motionless and then died. There was 

 some indication that this spreading out of the 

 cells was accompanied by a taking xip of fluid 

 from the surrounding medium and that this led 

 to processes of solution which initiated the re- 

 trogressive changes. ^' 2. * 



In order to prolong the life of these cells it 

 was therefore necessary to retard this exaggera- 



1 Leo Loeb, Journal Medical Besearoli, 1902, 

 II 145. Virclioiv's ArcMv. 1903, Vol. 173, 35. 



2 Leo lioeb, Folia Eaematologica 1907, IV 313. 

 FfUiger's ArcUv. 1910 Vol. 131, 465. 



3 Leo Loeb, Arcliivj f. EntwicTcelu)igsmech. 1898 

 VI 297. Anatomical Eecord 1912, VI 109. 



ted stereotropic response which led to a spread- 

 ing out of the cell in contact with the solid 

 body. We found previously that this can be 

 done not only by keeping the cells at a lower 

 temperature, which retards other activities as 

 well as the stereotropic reactions and is there- 

 fore not specific, but in a specific manner by 

 enabling the cells to rest on a surface previous- 

 ly covered with a thin film of paraffine or va- 

 seline. * In contact with such a surface the 

 spreading out of the cells is considerably re- 

 tarded and the life of the cells and the dura- 

 tion of their amoeboid movement is prolonged. 

 In carrying out these experiments, we make 

 use of the experimental cell fibrin (amoebocyte) 

 tissue, a small piece of which we place on the 

 prepared surface and surround with the de- 

 sired kind of fluid. 



Last summer at the Woods Hole Marine Bio- 

 logical Laboratory we continued these experi- 

 ments with the cooperation of Mr. K. C. 

 Blanchard ■' and found an additional method of 

 preventing the extension of the cells and thus to 

 prolong their life and activities. This can be 

 accomplished by making the medium into which 

 the cells enter from the piece of tissue very 

 slightly acid, an observation which agrees with 

 our previous finding according to which the 

 cells perish in a neutral solution of isotonic 

 sodium chloride, but are preserved in such solu- 

 tions after addition of a very small amount of 

 either acid of alkalL- 



In our recent experiments we found that in 

 such slightly acid media the cells leave the 

 tissue in dense masses and continue to move 

 for a considerable period of time; they are 

 preserved, their spreading out is much retard- 

 ed and their motor activity in consequence 

 much prolonged. In alkali the cells are like- 

 wise preserved for some time, but they begin 

 to spread out and become dissolved much earlier 

 than in acid. 



It is possible to grade the effect of acid upon 

 the cells. If the acid used is too strong and 



4 Leo Loeb, Washington University Studies 

 1920 VIII 3. American Journ. Physiol. 1921, 

 Vol. 56 140. 



5 These experiments will be more fully described 

 by the writer and Mr. K. C. Blanchard elsewhere. 



