X-rays on Plant Cells. 
* 
protoplasm had retreated. The tannin must therefore have been capable of 
diffusing out as well as the K 2 Cr 2 0 7 diffusing into the protoplasm. 
Work which has already been done points to a relationship between 
intensities used and time of exposure needed to bring the cells to this last 
stage. It is hoped to deal with this quantitative aspect in a later paper. 
Summary. 
Strips of tissue from the upper surface of the petiole of Saxifraga 
umbrosa were subjected to X-rays. 
1. Small doses of radiation are said to accelerate circulation, but in this 
material a depression follows, and there is no return to the normal in twenty- 
four hours. 
2. There is evidence of a lowering of the viscosity of the protoplasm 
in the early stages of radiation. 
3. From the time any change is seen in the protoplasm that change is 
irreversible. 
4. There is no direct influence of the rays upon the anthocyanin or the 
chlorophyll. 
5. The protoplasm allows the diffusion of solutes from the vacuole, and 
appears to become coagulated. 
6. By the time a precipitate can be obtained with the potassium 
dichromate used as a test for increased permeability all movement of the 
protoplasm has stopped. 
The Sir John Cass Institute, London. 
Literature Cited. 
1 . Williams, M.: On the Influence of Immersions in certain Electrolytes upon Cells of Saxifraga 
umbrosa. Ann. Bot., Oct., 1922. 
2 . Lopriore, G. : Azione dei raggi X sul protoplasma della cellula vegetale vivenle. La Nuova 
Rassegna, 1S97. 
3 . Schaudinn, E. : Uber den Einfluss der Rontgenstrahlen auf Protozoen. Pfliigers Archiv, 
1899. 
4 . Packard, C. : Journal of Gen. Physiology, vol. i, No. 1, 1918. 
5 . SVEDBERG, T.: Zeitschrift f. phys. Chem., No. 71, 1910, p. 571. 
Q 
