AND CONTENTS OF THE MOUTH. 167 



The isolated bacilli or articulations are from 2 to lo micro-mille- 

 metres ; their thickness is from i to i'3 mm. Of the primary 

 fungi of the mouth this is the greatest ; all its parts cannot be 

 coloured with iodine (Fig. 14 of Miller to be compared with our 

 Fig. 2, w, w, n^ ;?, n\ q, r, and with Fig. 5, a, b, c, d). It is not 

 detected in the dental tubuli, probably because it is too big to 

 penetrate there. 



Miller holds it to be of a different species from Leptothrix 

 innominata, from its size, and through possessing segmentations or 

 knots, and not bending in zig-zag ; and also on account of its 

 very strong behaviour towards iodine re-agents. But these points, 

 very feeble in themselves, are not even constant. Take, for 

 example, the specimen drawn in Fig. 9, d^ in which the filament 

 of Leptothrix (fertile filament not segmented) springs from a por- 

 tion of the chain which rose on the top of a large, knotty filament. 

 If these large filaments appear in stumps or in separate networks 

 it is owing to the growth of superior vegetation and the subse- 

 quent rubbing off of the latter by friction. 



I shall presently show that Leptothrix living in the water is abso- 

 lutely identical with this Bacillus maximus of Miller. 



I have, however, to observe that very distinct segmentations 

 exist sometimes, even in the most slender filaments. In Fig. 5,^, 

 I observed an opaque segment, deeply coloured in the middle, 

 with two clear, pale segments at the ends. This filament^ com- 

 pared with bacillus d (same figure), hardly gives the thirtieth part 

 of its thickness. Miller himself, in his previous work of 1883 on 

 Leptothrix gigantea, describes small rods and cocci within the 

 sheaths of filaments of the said Leptothrix (Figs. 2, 3, and 4 of 

 relative plate). In Fig. 5 he even drew a cumulus of small rods, 

 sprung out of the filaments through bursting. The very slender 

 filaments drawn in Figs. 2, 3, and 4 are also articulated. 



Leptothrix buccalis maxima.— The same author is not certain 

 whether this is a really separate species or a younger form of the 

 same Bacillus buccalis maximus. The only difference consists in 

 its resisting an iodine reaction, and in the greater distance of its 

 articulations. 



