58 THE AMKRICAN MONTHLY [Fel.niaiy, 



i{V(Ti:Hi(H.(KiV. 



Stainingthe Capsulesonthe Micrococcus Lanceolatus. — 

 I'rof. Wckh {Jo/ins Ilof^kiiis Ilosf^it.i! /htllilin. /// {iSgj), p. 

 JJ^) lias ilcscrilictl :i new inctliod tor staiiiin<j tlii" capsules on the 

 Micrococcus lanceolatus. It is as follows : Covcr-<;lass picpara- 

 tions niaik- without water from the tissues of rabbits or other ex- 

 perimental animals dead from the inoculation of this jjerm are 

 treated first with glacial acetic acid, which is at once allowed to 

 tlrain otVand is replaced (without washing; in water) with aniline- 

 oil, jjentine-violet solution. The staininjj^ solution is repeatedly 

 added to the surface «f the covcr-j^lass until all of the acid is dis- 

 placed. If now the specimen is washed with a saturated aqueous 

 solution of the common salt and is examined in tliis solution, it 

 will be seen that both coccus and capsule are uniformly and deeply 

 stained and cannot be ditVerentiated. If water be used instead of 

 saturated salt solution, the capsides are decolori/.eil, sometimes 

 onlv in part when thev can be clearly recoj^ni/.ed. but often com- 

 pletelv, and the\ mav entirely disappear. By usinij weak solu- 

 tions of salt it is possible in ail cases to din'ereiitiate tiie capsule 

 if it is present. 'I'lie strenj^th of the solution best adapted to dif- 

 ferent cases \aries. Often the ortlinary physiological solution 

 suffices. A generally useful strength is two per cent. The speci- 

 mens are to be examined in the salt solution. When mounted in 

 balsam the capsules do not always remain distinct. The capsules 

 may appear stained throughout, or only their outer margin may 

 be stained. This method of staining was worked out on the sup- 

 position that the capsules are composed essentially of mucin, which 

 is precipitated by acetic acid, and vyhen thus precipitated is in- 

 soluble in concentrated salt solution and swellsup in water. The 

 chief adyantages of this method are the dilTiculty of ayoiding pre- 

 cipitates of the dye. and the alterations in the cells and other ele- 

 ments, but in difficult cases it will serye a useful turn, although 

 less violent methods when applicablo are to be preferred. 



The capsules vary in their structure, some being much more 

 delicate and narrower than others. In old exudates the capsules 

 are often very distinct and resistant to the action of water, in which 

 they may appear even quite highly refractive. The Micrococcus 

 lanceolatus stains readily on cover-slip preparations with the ordi- 

 nary aniline dyes. It is less easily stained in sections. In these 

 it can be stained by Gram's method, but VVcigert's fibrin stain 

 gives better results. The number of cocci brought to view by this 

 last method in sections of human lungs aflccted with lobar pneu- 

 monia is often very great, and the presence of the majority of the 

 cocci inside of leucocytes is clearly demonstrated. 



Some Facts about Lustgarten's Method for Staining 

 •Syphilis Bacilli. — M. .Satiuuiaud ( Annales Inst, rasteur, fSy2, 



