applies to certain. water bacteria as well'), but others again, 
sich as the thermophile bacteria, must necessarily have a very 
_ limited range. Now the conmoner putrefactive bacteria in 
Europe appear to have a comparatively low optimal tempera- 
tare for growth, that for Bacillus liquefaciens vulgaris Beyerinck 
being from 20° C. to 25° C. or even less, whereas in the tropics 
the air temperature may rise well above this limit, while the 
chemical changes going on in a putrefying mass in themselves 
generate heat and thus may cause a further rise of tempera- 
ture. I was able however in the Buitenzorg laboratories to 
isolate B. liguefaciens vulgaris from various putrefying fluids, 
and to show that it is apparently very widely distributed, but 
it is quite possible that various putrefactive bacteria which 
are common in Europe may be replaced by different forms in 
the Tropics. It seems probable however that the more rapid 
decomposition which goes on in a tropical climate is simply 
due to the fact that the average temperature approximates 
more closely to the optimum for the development of putre- 
lactive bacteria in spite of an occasional excessive rise, than it 
does in middle Europe and at the same time it must Re 
membered that the evaporation of water froma decomposing 
organic mass will tend to lower its temperature. The above 
tmarks apply only to the comparatively equable and moist 
chmate of Java. In a dry tropical climate organic matter a8 
4 general rule dries up before it has undergone any marked 
bacterial putrefaction and the subsequent process of ae 
station is a slow one, but in such dry climates the amount : 
organic material annually produced 1s also slight an 
on the whole an approximate balance is miner 
: Until comparatively recently Plant Phy siology sp i. 
3 vided in Europe only, but it is now being — ride 
Oceans and in the tropics a vast and alm a 
tld lies Open to the plant physiologist. With the former 
latter, every 
@ not at present concerned, but as regards me 
Oo ree 
1 
+) Annals of Botany. Vol. XI, 1897, p. 486. 
