COXTTilRUTlONS TO THE CyTOLOGY OF THE JJACTEEIA. 465 



system of metacliromatic granules. Sucli a supposition lias 

 already been considered aud rejected by both Schaudinn and 

 Gruilliermond. I have also had occasion already to speak 

 against this view, and I shall now entei- into it more fully. 



TheBacilli of the spirogyra type which I have described, 

 also the Micrococci, and Spirilla with a filamentar or 

 spherical nucleus, are in the majority of cases entirely free 

 from granular inclusions in the cytoplasm. The nuclear struc- 

 tures which 1 have described are the only constant internal 

 structures present. It is therefore useless to argue about meta- 

 chromatic granules in these forms, unless it be assumed that 

 the nuclear filaments, etc., are metachromatic bodies — an 

 assumption for which there is not a shred of evidence, aud 

 which is entirely opposed to the fjicts. It remains therefore to 

 consider the Bacilli and Spirilla (chiefly the organisms 

 of the flexilis type, aud the Spirilla from the frog and 

 cockroach) in which I have described a chromidial nucleus. 



In the first place, I must point out that the two methods of 

 staining — namely the Heideuhain and Romanowski methods 

 — which I have chiefly used are not sufficient to distinguish 

 between chromatic and metachromatic substances by means 

 of differential staining. ]>oth chromatic and metachromatic 

 granules are stained black with Heidenhain aud red with 

 Romanowski. Neither method, therefore, can be used as an 

 index of the chemical nature of the granules. In the second 

 place, I think it highly probable that metachromatic granules 

 do exist, side by side with the nuclear granules, in many 

 Bacteria with chromidial nuclei (cf. also Schaudinn [1903], 

 and Guilliermond [1908]). Bacillus flexilis itself, and 

 also other Bacilli of the same type, contain granular in- 

 clusions which may easily be stained intra-vitam with 

 neutral red, methylene blue and Brillantcresylblau. All 

 these granules have a faintly reddish tinge when so treated. 

 The same is true of Spirillum monospora. These 

 colourable granules are few in number, however, as con:pared 

 with the number visible after Heidenhain or Romanowski 

 stainino-. I believe therefore that thev are metachromatic 



