CHEMOTROPISM 149 



I then attempted to find some substance which could give a ehemo- 

 tactic stimulus to spermatozoa. The substances tested were such as are 

 known to give a directive chemical stimulus to many protozoa, the sper- 

 matozoa of ferns, pollen-tubes, etc. The following solutions were tried 

 by the capillary tube method: distilled water; meat extract 1 per cent.; 

 KNOs 10 per cent., 2 per cent. ; NaCl 5.8, 2.9, 0.58 per cent. ; K* malate 

 1, 0.1 per cent. ; asparagin 1 per cent. ; glycerine 5 per cent. ; grape sugar 

 18, 9, 4.5, 2.25 per cent. ; peptone 1 per cent. ; alcohol 50, 25, 10 per cent. ; 

 diastase 1 per cent.; oxalic acid 0.9, 0.09, 0.009 per cent.; nitric acid 

 1, 0.1, 0.01 per cent. 



No definite chemotactic reaction neither attraction nor repulsion 

 was observed in any case. Into tubes containing the weaker solutions 

 the spermatozoa went in and out with apparent indifference. . . 

 On coming into contact with strong acid solutions (oxalic acid 0.9, 0.09 

 per cent.; nitric acid 1, 0.1 per cent.) the spermatozoa were killed, and 

 thus formed slight collections. They were thus not able to avoid acids by 

 means of a negative chemotactic reaction. 90 



Other authors, e.g., Dewitz and the writer, have also 

 reached the conclusion that the egg of the sea urchin con- 

 tains no substance for which the spermatozoon of the 

 same species is positively chemotropic, and that Buller's 

 conclusions that positive chemotropism plays no role in 

 the entrance of the spermatozoon of sea urchins into the 

 egg is correct. 



F. Lillie has recently expressed the opposite view, 

 namely that the egg of the sea urchin contains a substance 

 to which the spermatozoa are positively chemotropic and 

 to which he gave the name ' l f ertilizin. ' ' 283 He first 

 tried Pfeffer's correct method with capillary tubes with 

 negative result, just as Buller and the rest of the obser- 

 vers. Instead of concluding that the spermatozoa are 

 not chemotropic he discarded the method and used Jen- 

 nings 's method, stating that it gives "incomparably more 

 delicate results than Pfeffer's method of using capillary 

 tubes " (p. 533). Lillie found with this method that the 

 spermatozoa of Arbacia are positively chemotropic to 



