AND CONTENTS OF THE MOUTH. 79 



in our Fig. 6, and the query will be asked : — Of what use are those 

 upright, barren shoots resembling grass, which have been eaten 

 close by cattle ? This want of fruits cannot be accounted for by 

 mechanical injuries. The figures of Robin, Frey, Miller, and 

 others do not suggest a different conclusion.* 



After these reflections, we were induced to investigate this 

 parasite. Our researches will be particularly demonstrated in 

 Section 4, only a synthesis of them being given here. 



From our observations Leptothrix buccalis would, therefore, 

 live under four forms, or have four different stages of development, 

 according to the conditions of the alimentary substratum. 



In the liquid secretions, as saliva and mucus, its spores -bac- 

 teria and cocci — and its gemmiferous sprouts — real bacilli (exclud- 

 ing the Spirilla, the 7iail-like^ the snake-like^ and the comma) — 

 increase and multiply like moving spores and germs of fungi. 

 This would be the immersed vegetatioji of Leptothrix. 



The bacteria, the yeasts, and the spores have generally the 

 power of reproducing the full organism like the seeds of the 

 phanerogams ; but, between the spores of the bacteria on one 

 side, and the seeds of the phanerogams on the other^ there is this 

 difference : that those seeds cannot multiply by division, produc- 

 ing fresh seeds ; whilst moving spores, yeasts, and bacteria multi- 

 ply abundantly, by fission, even by themselves. 



If, however, the liquid is kept quiescent in the crypts or cavi- 

 ties, or if the part is, as on the surface of the tongue, very firm, 

 the second period or low vegetation begins, viz., beaded^ chain-like^ 

 and bundle-like bacteria are formed, so common on the patina of 

 the tongue. But vegetation stops where (as in the mucous parts) 

 the continual friction impedes a further formation. 



In the secretions and mucus there is a relative inactivity; but 

 if it becomes effective, a reproductive growth will be formed, as 

 shown in Fig. 16, taken from puhnonitic sputum, which for 

 several days had adhered in the interior of a closed tube. 



The third period, or growth, is when it lodges on a solid part, 



* Bizzozero, Manuale cit. nella Bibliografia, PI. II., Fig. 27 ; Robin, His- 

 toire naiurelledes vegetaux, etc., 1853 (see Bibliography), PI. I., Figs. I and 2. 

 Frey, figure reproduced by Perroncito, quoted in Bibl., Fig. 1 1. Miller, 

 figures quoted later on. 



