540 
BEES AND BEE-KEEPING. 
detects the difference, for if a speck of the interior 
of a larva, dead through cold or neglect, be placed 
on a glass slip, covered down in the usual way, and 
then examined by a good Jin. or Jin. objective, the 
field will be well-nigh covered with fat and other 
cells, not looking very unlike those taken from a 
healthy larva, as at B, Plate I. Although the descrip- 
tions given will enable the bee-keeper to pronounce 
pretty certainly upon the presence of foul brood, cases 
do occur in which nothing but a microscopic examina- 
tion will settle the point beyond the possibility of doubt. 
Before discussing the nature of foul brood, it is 
necessary to give some attention to the before- 
mentioned micro-organisms, to the presence of which 
is due, not only infectious diseases, but also all fer- 
mentive and putrefactive changes. To them the general 
name of Schizomycetes, or fission fungi, has been ap- 
plied, because their method of increase is by splitting, 
or fissuration. They are divided into four genera : 
Micrococcus, Bacterium^ Bacillus^ and Spirillum. 
There are many species of each, and they may be 
classed as septic, or causing putrefaction ; zymogenic, 
causing definite chemical changes, as lactic fermentation 
in the souring of milk ; chromogenic, or colour-forming, 
because in masses they bear certain distinct tints ; 
and pathogenic, or disease-producing ; and it is here 
vital to note that those organisms only which are 
capable of growing and multiplying in the tissues 
of an animal are pathogenic to that animal, their 
presence immediately establishing a diseased condition. 
Other organisms, even if artificially introduced into 
healthy tissues, suffer rapid destruction. 
