422 



ACTINOMYCETES. 



very closely related to the tubercle bacillus. These organ- 

 isms, which are often a little shorter than the T. B. , are 

 found in the specific new-formation (nodes and nodules) 

 of leprosy in the various organs in cases of the disease, 

 and often in enormous numbers. The bacilU are found in 

 groups, the individuals being parallelly arranged, and lie 

 within special "lepra cells," which have recently been 

 explained, sometimes as confluent, proliferating lymph 

 endothelium, sometimes as lymph thrombi. 



By means of staining reactions the L. B. cannot be cer- 

 tainly differentiated from the T. B. They stain by the 

 Koch-Ehrlich method just as well as the T. B., and, like 

 them, are also stained by Gram's method and by a suffi- 

 cient action of aqueous anilin dyes. A diflerence is said 

 to consist in this, that the L. B. is so well stained in six 

 or seven minutes with an aqueous solution of f uchsin that 

 good preparations are obtained after washing with water, 

 while the T. B. is not; on the contrary, alkaline methyl- 

 ene-blue stains the T. B. quicker than the L. B. Compare 

 the controversies upon this between Baumgarten and 

 Wesener (C. B. i, 450, 573; n, 131, 291). 



Still, all authors are now agreed that the staining reac- 

 tion cannot help much in the differential diagnosis, no 

 more than the form of the bacilli, ^ from which it follows 



1 The following difference in sections is given by Spiegel from 

 Unna's laboratory (C. B. XXI, 817): 



These differences are naturally never so typical as here appears. 



