a 
_in heated cultures originated from sporiferous germs 
3904 The Botanical Gazette. [October, 
colonies in the cultures on successive days get an approximate : 
idea as to the actual condition of the bacteria in the sample 
when it was taken. This method is of course only applicable 
under certain conditions, for if there is a great variety in the 
number of different species, the rate of development of the — 
various forms may vary to such an extent as to impair the — 
accuracy of this method. a 
The method, however, possesses a certain value in thecase 
in hand as the number of species is not large and as it affords 
a check on the second method which is experimental. 
The other method consists in destroying all jforms that are 
in a vegetative state by sterilization at a low temperature, 
This temperature should not be high enough to injure the 
germs that are already in a dormant state but should be suffi 
cient to kill all forms having protoplasm in an active condition. 
The quantitative determination of the bacteria in equal vol- 
umes of the sample of water or diluted mud before and after : 
this sterilizing process affords us data for this problem. : 
Unequal distribution of the germs in the different cultures : 
will materially affect this result, but if proper pipe > # 
taken to thoroughly distribute the bacteria in the fluid oa 
the control cultures are made, this element of error 1s mater — 
ially reduced. ‘ 
Samples of water as well as of mud were subjecte ; 
method of differentiation and were sterilized for one ee 
the temperature of 70° C. This temperature ts coms! por 9 
higher than any known form of active protoplasm can "elope ? 
so that one may be absolutely sure that all colonies dev 
d to this 
Ten series of tests were made with samples 
water at varying depths and in all but 
‘“theated” cultures developed bacteria in greate: 
bers. The percentage of sporiferous bacterl acted 
varied widely and in two instances t 
this partial sterilization showed nearly as 0 
those untreated. Bacteria, in a spore condition seri i 
strated in the superficial water layers as well as at : 
and intervening depths. the 
Ten series = ‘eure were also made upon the nd 4 
sea bottom. These likewise showed a varying as condi- 
the bacteria present on the sea floor to be in a Fes 
according to Miquel a8 
bottom — 
*Except two or three thermophilous species, 
