ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
789 
Metschnikoff, however, denied this, and proved that the living fluids 
of immune white rats form a most excellent cultivating medium for the 
bacilli of anthrax. These observations of Metschnikoff, according to 
Buchner, might be explained by the fact that Metschnikoff in his experi- 
ments introduced more bacilli than could be destroyed by the living 
fluids of white rats, as a certain quantity of serum was able to destroy 
only a very small quantity of micro-organisms. Speaking of the experi- 
ments made by his pupils Ibener and Roeder, he stated that, when a 
certain kind of micro-organisms were placed into a given quantity of 
serum, the micro-organisms might either be destroyed in toto , or repro- 
duce themselves in large numbers according to the number of micro- 
organisms introduced in the first place into the serum. When, instead 
of placing the micro-organisms directly in contact with the serum, the 
micro-organisms were wrapped up in sterilized cotton-wool, it was found 
that the bacilli, so protected against the temporary harmful influence of 
serum, began to grow luxuriantly at the end of twenty-four hours. The 
bactericidal power of serum disappeared, therefore, shortly after death. 
Massart, Bordet, and Gabritchewsky had previously proved that the 
emigration of leucocytes to the spot where the virus was introduced was 
due to the attracting influence (positive chemotaxis) of the chemical 
poisons secreted by micro-organisms, but he (Buchner) was of opinion 
that the substances dissolved in the cultures have hardly any action on 
leucocytes, but that this attracting influence on leucocytes was due 
to the protein present in bacterial cells themselves. Whereas the 
products of the metabolism of micro-organisms had little or no attract- 
ing influence on the leucocytes, the proteins themselves attracted the 
cells most powerfully. 
As long as the bacterial cells were active and capable of reproducing 
themselves actively, the proteins were contained in the cells, and these 
poisons only left the cells when the latter became diseased or old. 
Hence these proteins were chiefly found in old cultures, the filtered and 
sterilized extracts of which always possessed a strong attracting influence 
on leucocytes. Hence it followed that, “ The more a given micro- 
organism is harmfully influenced by the living fluids of a given species 
of animal, the more proteins will be excreted. This, as a natural 
consequence, is followed by a corresponding increase in the number of 
cells which emigrate to the point of inoculation.” In every case the 
living fluids of the body exert a harmful influence on micro-organisms, 
and then, when in consequence of this the excretion of proteins takes 
place, the amoeboid cells emigrate to the spot. 
Turning now to the characteristics of this germicidal substance 
present in serum, he thought that its germicidal power gradually dis- 
appeared, so that after a few days the serum had no bactericidal power. 
This germicidal action was destroyed by the micro-organisms themselves, 
for, unless the latter were completely destroyed, they soon began to 
grow freely in serum. Serum maintained at 55° C. during half an hour, 
or at 52° C. during six hours, loses its bactericidal power completely. 
A moderate degree of warmth (37° C.) intensified the germicidal action 
of the blood or serum. 
Turning now to the question as to whether this bactericidal action 
of the blood had any share in the production of immunity, he gave 
