OF MICRO-ORGANISMS. 91 



whether, by increasing the degree of concentration, a 

 point would not be reached where attraction would 

 change to repulsion; he has not made the experiment, 

 but he has noticed that great numbers of spermato- 

 zoids still penetrate into the tube "when contain- 

 ing a solution in the proportion of 15 to 100, not- 

 withstanding the fact that they there meet a speedy 

 death. 



The general conclusion to be derived from these 

 numerous experiments is, first, that the spermatozoids 

 are sensible to certain chemical excitations, and conse- 

 quently, that in every group of plants there exists a 

 special substance acting the part of a specific excitant 

 towards the spermatozoids. The author does not hes- 

 itate to regard the spermatozoids as a physiological 

 re-agent of such substances, allowing feeble traces of 

 the same to be detected in a liquid solution. He thus 

 comes to form a spermatozoi-d test, which is not with- 

 out analogy with the Bacteria test, invented by En- 

 gelmann. An application of the test is the following: 

 a decoction of herbs having presented the property of 

 attracting the spermatozoids of Mosses, the author 

 concluded that the decoction must contain cane- 

 sugar. 



VIII. 

 THE PHYSIOLOGICAL FUNCTION OF THE NUCLEUS. 



It would be of the highest importance to know 

 what is the seat of the phenomena of the life of re- 

 lation in the bodies of Micro-organisms. We have 

 seen that Micro-organisms are the equivalent of a 

 simple cellule, composed, according to the classic 

 plan, of a protoplasm, of a cellular nucleus, and of an. 

 enveloping membrane. 



