INVERTEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC. 489 



the air as bacteria and mould-spores. The neighbourhood of the 

 different trees could not with certainty be stated to have any percep- 

 tible effect on the organisms contained in the air. 



Observations were also made on the pellicles which appear on the 

 surface of fermenting fluids. The temperature 30^-34;° C. was found 

 the most favourable to the production of Mycoderma aceti and Pas- 

 teurtanum. At low temj)eratures Saccharomyces Mycoderma prevails 

 almost exclusively ; but as the temperature rises it gives place to 

 microbacteria ; 15° C. is its optimum temperature ; above 26^ C. 

 it is unable to thrive. At high temperatures, as above 35° C, 

 Bacillus subtilis and Spirillum tenue are the prevailing forms ; but the 

 former can exist at any temperature above zero. 



The auth(rt' is unable to confirm the statement of the Eussian 

 physiologist Horvath that rest promotes, while motion retards the 

 production of ferments in general. 



Vital Power of ScMzomycetes in Absence of Oxygen.* — J. W. 

 Gunning has previously published an account of his researches, from 

 which he draws the conclusions that substances capable of putrefac- 

 tion when enclosed in vessels from which nearly all oxygen has been 

 removed, act only for a short time ; and when oxygen has been com- 

 pletely removed by means of a solution of grape sugar in caustic soda 

 mixed with indigo, no putreftiction occurs, and the organisms which 

 produce putrefaction are killed. 



The present pajicr is a reply to Nencki's objections, who con- 

 sidered t that Gunning's experiments were inaccurate. Gunning has 

 shown that the apparatus employed to produce what Nencki termed 

 " space freed from oxygon " is insufficient for that purpose, and 

 that it contains enough oxygen to colour ferrous ferrocyanide deep 

 blue. Nencki also suj)poscd that the presence of products of fer- 

 mentation stopped all action of the organisms. To controvert this 

 statement. Gunning adduces experiments which were already in pro- 

 gress before Nencki had published his objections. These consisted in 

 keeping putrefying matter in tubes in which oxygen, hydrogen, and 

 air were enclosed. As was to bo expected, fermentation proceeded 

 furthest in the tubes containing pure oxygen, less far in those contain- 

 ing air, and very much less in tliose containing hydrogen. The 

 amount of decomposition was ascertained by estimating the carbonic 

 anhydride, ammonia, and volatile acids. Nencki's last objection was 

 that by some cliancc the liquids affected may have come in contact 

 with only those bacteria which require oxygen for their existence. 

 This objection is shown by Gunning to depend on a misunderstanding 

 of Pasteur's researches, viz. that two such varieties exist. Pasteur 

 believes tliat such ferments as exist at the sxu'face of a putrefying 

 medium obtain oxygen from the air, and those in the interior t)f the 

 liquid derive oxygen from the decomposing substance, but does not 

 imagine two varieties to exist. Besides, oven were there such different 

 organisms, it is impossible to believe that from some clianco a liquid 



• 'Jonm. prakLChcm.,' xx. p. 431 ; sco Mourn. Chcm. Soc.,* Abslr., xx.xviii 

 (1880) p. '277. 



t StD this Joumal. iii. (ISSn) p. y^2. 

 VOL. III. 2 K 



