NECROSIS 381 



witliout producing directly evident alterations, harms or kills all 

 living protoplasmic structures." HgCla is such a poison, whereas 

 H2SO4, bromine, and similar substances that destroy all life through 

 their strong chemical action are not included in this category. The 

 j)rotoplasmic poisons presumably act by combining with one or more 

 of the constituents of cell protoplasm; e. g., HgCL i)robably combines 

 with the proteins, chloroform with the cell lipoids (physically?). By 

 means of his special teehnic Barber^- is able to introduce minute 

 quantities of poisons into living cells and observe their effect on the 

 cytoplasm; HgCl2 is thus found to be most toxic, while AS2O3 is 

 relatively inert. Mathews'-^^ has shown that the toxicity of ions 

 depends on the ease with which they part with their electrical charges, 

 and the toxicity of a salt is a function of the sum of the toxicity of 

 the ions; hence the toxicity of a salt is in inverse proportion to its 

 decomposition tension. Kunkel suggests that oxalic acid and fluorides 

 are poisons because they combine the cell calcium, and barium salts 

 may be poisonous because they precipitate the SO4 ions. We can 

 readily imagine that the combining of even one of the essential con- 

 stituents of the cell may so upset the normal chemical processes that 

 the cell no longer takes up substances to repair its waste, and hence 

 necrosis ensues. ^^ 



Physical agents may cause necrosis, usually in ways too obvious 

 to require explanation. With most cells, large portions of the cyto- 

 plasm can be destroyed without serious results, for so long as the 

 nucleus is intact the cytoplasm can be reconstructed. The fact that 

 necrosis frequently follows relatively slight injuries of the nucleus 

 is perhaps best explained by considering that injury to the nuclear 

 membrane modifies the permeability of the nucleus for substances in 

 solution, which might readily affect its metabolic activities to a serious 

 degree. It is possible, also, that solvents of lipoids, such as chloro- 

 form, etc., produce much of their deleterious effects by modifying 

 the permeability of the cell, if the semipermeability of cell mem- 

 branes depends largely upon the lipoids they contain. ^^ 



Physical injury of even slight degree may bring on severe alterations 

 in cells, however, and indeed may cause severe chemical alterations. 

 We know that many chemical reactions can be brought about by slight 

 mechanical disturbances, e. g., the explosion of fulminate, nitrogen 

 iodide, etc., and it is quite possible that mechanical disturbances can, 

 likewise, cause chemical changes in the protoplasm. JNIechanical 

 injury of cells under the microscope results in an apparent increase 



52 Jour. Infect. Dis., 1911 (9), 117. 



'3 Amer. Jour. Physiol., 1901 (10), 290; NichoU, Jour. Biol. Chem., 1909 (5), 

 453. 



^* It is hardly profitable here to go further into the theories of the action of 

 poisons, which are generally extensively considered in the treatises on toxicology 

 and pharmacology (also by Davenport, loc. cit). 



5^ See Pascucci, Hofmeister's Beitrage, 1905 (6), 552. 



