65 



under o}).serv;ition for an additional 24 days, during:' which tinio a great 

 change took phice in one of them, tlie growth increasing tenfold. 

 This increased growth of the organism was due to no diastasic action 

 of its own. l)at to the diffusion of maltose or dextrin liberated from 

 the starch by some buried, slow-growing, w^hite, starch-converting col- 

 onies, which originated from spores that found their way into the starch 

 during its })reparati()n and wliich passed through the steamings 

 uninjured. 



The foregoing conclusion is also supported by the fact, already set 

 forth, that l*.s. Jn/arhit/u' grows well on a variety of crude vegetable 

 substances rich in sugar. That this feeble diastasic action partially 

 accounts for the fee))le parasitism admits of little doubt. Proliably 

 its feeble cytohydrolytic action and its strict aerobisui are also restrain- 

 ing influences. 



AEROBISM. 



As already noted, the ])uried colonies of Ps. JiyavintJil in plate cul- 

 tures grew slowly, and those deepest in the layer of agar or gelatin 

 remained smallest. In the stab cultures also the bacteria gradualh' 

 faded out in the depths, making much the best growth near the surface. 

 The additional results bearing on the inability of this germ to grow 

 in the absence of free oxygen are thrown together in the followinor 

 paragraphs. 



Fermentation Tubes. 



The form of tube used in my laboratory is that devised by Dr. Theo- 

 bald Smith and made by E. Greiner, of New York.^ This, l)y reason 

 of its size and shape, the writer has found more satisfactory than sev- 

 eral other sorts he has tried. 



First is a table, which sets forth the results o))taincd with fermen- 

 tation tubes in 1897. The tubes were tilled with distilled water con- 

 taining 1 per cent of Witte's peptonum siccum and 1 per cent of the 

 sugar or other substance to be tested. 



^ The fermentation tube, with special reference to anaerobiosis and gas production 

 amontr l)acteria. The Wilder Quarter Century Bo<ik, Ithaca, X. Y., 1893, p. 187. 



il788 — No. l!8 — Ui 5 



