BY R. GREIG-SMITH. 297 



containing maltose 2%, ammonium sulphate 0*04-0-06%,*, 

 potassium citrate 0*5% and agar 2%. Phosphate (0*5%) gives 

 rise either to short cocco-bacteria or to short rods, while citrate 

 produces long rods. 



It is obvious that with an organism which varies so much, and 

 which has baffled so many investigators, one must endeavour to 

 obtain large cells in order to see the inner structure. So far as 

 I know, this has not hitherto been done; but during this research, 

 as has been already mentioned, large forms were obtained when 

 maltose, citrate and ammonium sulphate were contained in the agar 

 medium. But the difficulties connected with a clear and sharp 

 staining of the cells were not overcome by growing a large-sized 

 microbe. There is always some slime produced, sometimes in 

 quantities so small as to be' inappreciable except when one 

 endeavours to determine the structure of the cells. The slime is 

 a disturbing element, for it is in most cases stained as deeply as 

 the chromatin. This applies to the slime without the cells. 

 If there be slime within the cells, there is little wonder that the 

 recognition of the structure has been so difficult. An examination 

 of over thirty anilin dyes showed that the slime in bulk was 

 coagulated and coloured by all except eosin and methyl-green 

 (Grubler). But having previously obtained a good staining with 

 an old solution of carbol-fuchsin, I made experiments and found 

 that the best results were obtained with a weak stain containing 

 the following: — Fuchsin (Grubler) 0*1 grm., alcohol lOc.c, 1% 

 phenol 90 c.c. The method consisted in adding a large loopful 

 (5 mm. diam.) of the slime to 4 c.c. of distilled water contained in 

 a test-tube, and inserting the tube into a beaker of water at 80°. 

 The slime is, as a rule, speedily distributed in the water and a 

 uniform suspension of the cells obtained. Two c.c. of the stain 

 (at 80°) are added and the tube replaced in the water and kept at 

 80° for from 4 to 8 hours. By this treatment the solution does 

 not gelatinise upon cooling, and the cells remain uniformly 



* We have already seen that this salt produces an acid reaction of the 

 medium (p.280). 



