586 PHAGOCYTOSIS OF SOLID PARTICLES, ni 



Experiment 11 may correspond to the decrease following the increase 

 in Experiments 9 and 10. 



The comparative rates of ingestion of carbon and quartz particles 

 depend, therefore, upon the condition of the cells. Sometimes prepara- 

 tions of carbon and quartz have been made in which there was prac- 

 tically no ingestion of quartz. This may be seen in the photographs, 

 Figs. 8 and 9, where no quartz is seen inside the cells though there 

 is plenty available. 



As far as the writer is aware the experiments in this paper constitute 

 the first quantitative comparison of the effects of different kinds of 

 solid substances on living cells. Even qualitative comparisons are 

 limited. Aside from the effects of carbonaceous and silicious dusts 

 in the lungs the only recorded observations seem to be the mere 

 statement of Commandon (6) that starch is ingested by leucocytes 

 more readily than carbon. Schaeffer (7) endeavored to compare 

 the ingestion of carbon and glass particles by amebae but neither 

 was ingested. 



Phagocytosis of Carbon and Quartz by Sponge Cells 



This experiment was done at the Marine Biological Laboratory, 

 Woods Hole, with a small marine sponge, Grantia. The sponge was 

 squeezed into a test-tube, and a thick suspension in sea water of 

 active cells was obtained. 8 parts of this suspension were mixed with 

 4 parts of sea water concentrated to twice its normal strength by 

 boiling, 1 part of 0.2 M borate mixture (pH 7.5), 1 part 10 per cent 

 acacia neutralized with sodium hydroxide, and 2 parts of a suspension 

 of 3.2 micron carbon particles and 2.4 micron quartz particles in 

 distilled water. The result is a suspension of cells, quartz, and carbon 

 in normal sea water plus 0.6 per cent acacia to stabilize the carbon 

 and quartz, the alkalinity being approximately the same as that of 

 normal sea water. 



A sample of this mixture was allowed to run under a cover-slip 

 supported as for the film method and sealed with paraffin. The cells 

 were slowly ameboid and ingested the particles rather sluggishly 

 compared to leucocytes. After 5 hours at room temperature, counts 

 were made of the number of quartz and carbon particles found inside 



