830 THE POPULAR SCIENCE MONTHLY. 



sart, Bordet, and Gabrichevsky, that the leucocytes are attracted 

 by the chemical poisons secreted by the micro-organisms ; or the 

 protein of the bacterial cells themselves may bring them on the 

 spot, as is maintained by Buchner, who also has conclusive ex- 

 periments in favor of his theory. Only further research will be 

 able to decide which of these views is correct, and to what extent. 

 But under the present state of knowledge the question can not be 

 answered with certainty the more so as Behring, Kitasato, Buch- 

 ner, Emmerich, Vaillard, Tizzani, Cattani, Ch. Richet, and many 

 others have weighty arguments in favor of the opinion that the 

 immunity of animals depends upon some ferment-like albumin- 

 ous substance contained in the serum of their blood. Strenuous 

 efforts have been made of late by Koch, Buchner, E. H. Hankin,* 

 and many others to come to some more definite knowledge of these 

 " defensive proteins," which are known in science under the names 

 of " alexines," " sozins," " phylaxins," and so on. But it will prob- 

 ably take some time before our notions about these substances 

 take a definite form. One thing seems, however, to become more 

 and more certain namely, that the serum of the blood of immune 

 or vaccinated animals, although in many cases it does not destroy 

 the microbes themselves, is nevertheless possessed of a vaccinating 

 power. This fact is settled beyond doubt ; it is continually con- 

 firmed by fresh experiments ; and it is recognized by the follow- 

 ers of the biological theory as well. As to its explanation, it may 

 be sought for in the direction indicated by Metchnikoff namely, 

 that the serum, though not destroying the microbes themselves, 

 destroys the poisonous substances which they are developing in 

 the organism. In such case, organisms would be endowed with 

 two means of defense instead of one ; the two theories would 

 naturally complete each other; and, may be, in some not very 

 distant future they would enable man to combat with success 

 some of the worst microscopic enemies of the human race. 

 Nineteenth Century. 



A curious illustration of the indirect influence of the environment on human 

 character is given in Mr. Greswell's Geography of South Africa, where it is ob- 

 served that the indigenous woods of the country do not seem especially adapted 

 for boat and ship building. The dearth of good ship-timber must partly account 

 for the complete degeneracy of the Dutch colonists at the Cape as a seafaring peo- 

 ple. With no good harbors at hand, with no navigable rivers, and no ship-timber 

 for spars or masts, the change in their character and traditions as a maritime and 

 fishing folk to a nomadic, pastoral, and continental people, might almost have 

 been conjectured from the beginning. At the present time the up-country Boer 

 has extremely vague ideas of the ocean and of all things. 



* See the reports of the last Hygienic Congress held in London, in September, 1891. 



