ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 255 



cations of the canals ; the micrococci deepest of all. In the canals 

 may frequently be seen a gradual transition from the long to short 

 bacilli, and from short bacilli to micrococci. The schizomycete 

 causes pathological changes in the lower layers, stops up the canals, 

 and destroys the fibrilli, by which the transport of nutriment to the 

 outer layers is entirely cut off, and they, in consequence, die and 

 decay. The entrance of the fungus is always preceded by the attack 

 of acids. The fungi cannot remove the lime from the solid tissue of 

 the tooth, so that actual infection of a perfectly sound tooth by a 

 carious one cannot take place. The first stage of caries is therefore 

 a chemical one, the extraction of a calcium-salt ; the second a patho- 

 logical one, the death of the tissue by the destruction of the fibrilli 

 of dentine ; the third, a process of decay of the dead tissue. The 

 first and third of these stages can be reproduced outside the mouth. 



Bacilli in Condensed Aqueous Vapour of the Breath of 

 Phthisical Persons.* — A. Eansome condensed the aqueous vapour of 

 the breath of persons in an advanced phthisis, by the method he 

 invented some years ago (1869) ; the method of staining used was 

 that of Heneage Gibbes, magenta and aniline being used, discharged 

 by dilute nitric acid, and chrysoidin then added. It was found that 

 in the aqueous vapour obtained from two persons suffering from 

 phthisis, there was a bacillus which took the staining in the same 

 manner as the bacillus found in phthisical sputa and in tubercle, and 

 which is indistinguishable from that organism. In some cases the 

 experiments were unsuccessful. 



Bacillus tuberculosis."!" — Dr. H. D. Schmidt has published the 

 result of his investigations into Koch's Bacillus tuherciilosis, and asserts 

 that it is not a Bacillus but simply a fat crystal ! It is impossible to 

 deal seriously with the paper, notwithstanding that it is written by an 

 ex-President of the Pathological Society of New Orleans, who has 

 been occupied for some years in work with micro-organisms. 



Bacteria of the Air and Soil.| — In continuation of previous 

 experiments carried on in the laboratory in the Park of Montsouris, 

 P. Miquel gives the result of a number of observations on the 

 quantity of bacterial germs present in the air in different localities 

 under different circumstances. Notwithstanding temporary fluctua- 

 tions, a general law was observed with regard to the number of germs 

 present at different seasons of the year; as a rule, it attains its 

 maximum in autumn, its minimum in winter and spring. While rain 

 is falling, the number of bacteria in the air is greatly reduced ; it 

 increases as the ground dries, and again diminishes when the drought 

 has lasted for 10 to 15 days. The average number of bacterial germs 

 per cubic metre of air is given for the autumn quarter 142, the 

 winter quarter 49, the spring quarter 85, and the summer quarter 105. 



* Proc. Eoy. Soc, xxsiv. (1882) pp. 274-5. 

 t 'Louisville Medical Herald,' iv. (1883) pp. 459-76 (6 figs.)- 

 X Extr. de I'Ann. do Montsouris pour 1882, 118 pp. See Bot. Centralbl., xii. 

 (1882) p. 307. Cf. this Journal, iii. (1880) p. 837 ; ii. (1882) p. 88. 



