TEXT-BOOK OF BACTERIOLOGY. 257 



The acids remove the coloring matter from almost all parts of 

 the tissues, the nuclei as well, and leave only the rod-cells deep blue 

 on a pale background. In fact, this method yields really 'good re- 

 sults, but it is troublesome and difficult to carry out, since the acid 

 solution must be renewed each time. 



The more modern processes which serve for the decoloration 

 of sensitive bacteria in general are, therefore, preferable — i.e., 

 Weigert's anilin-oil method or Unna's drying method. If we wish 

 merely to display the rod-cells without particular regard to the 

 tissue, the method adopted by E. Kiihne is the best. Stain the sec- 

 tions for six to eight hours in carbol-methyl-blue, then decolor first 

 in diluted acetic acid and afterward in distilled water, next dry 

 them on the slide with the bulb-bellows, lastly give transparency 

 with xylol and mount in Canada balsam. 



Particularly in the nodules the bacteria are then seen in great 

 numbers, chiefly in small groups. The latter indicate by their 

 arrangement that they originally lay together in the interior of a 

 cell which afterward degenerated, and frequently the unmistak- 

 able remnant of a cell membrane is visible. As we might expect 

 from their rare appearance in the blood, they are, as a rule, not to 

 be seen in the vessels. 



Please notice particularl3'' that it is only in quite recent tissue 

 changes that the bacilli can be observed in large numbers and in 

 their characteristic arrangement, and that they are best seen in 

 quite young nodules in the spleen or lungs. When degeneration 

 has commenced and the destructioa of the newly-formed parts has 

 made some progress, the bacteria are destroyed along with the 

 rest, and therefore they are only to be found exceptionally in tha 

 ulcerous, purulent, ruptured glands and abscesses of the skin, etc. 



Their presence in such places, though probably in verj' small 

 numbers, is nevertheless proved bj' successful transmissions by 

 means of the pus. Loffler is certa.inly right in advising that for a 

 diagnosis of glanders in a living animal less reliance should be 

 placed on microscopical examination than on the result of the inocu- 

 lations to be performed on animals which prove regularly suscep- 

 tible, such as the field-mouse or the Guinea-pig. It will often be 

 found that attempts to inoculate glanders from pure cultures will 

 fail. The reason is that the glanders bacillus is one of those which 

 are subject to natural attenuation. While freshlj^-obtained cul- 

 tures will kill animals with certainty and within the time already 

 stated, one may often find in the fourth or fifth generation that 

 the bacilli begin to grow less poisonous and larger quantities must 

 be inoculated. The general effects take place more slowly or not 

 17 



