390 The Botanical Gazette, [October, 
plained in the same way as in those samples of water that far 
exceeded the general average. 
Not much of an idea can be gained from an average like 
this unless other conditions are taken into consideration. 
As there was a wide difference between the physical charac- 
ter of the sea bottom at the various places from which sam- 
ples were taken, the analyses have been arranged with 
reference to this point to see what effect the substratum had 
upon the presence of bacterial life. 
The opportunity for a comparison of this nature was all the 
more favorable at Woods Holl on account of the slight varia- 
tion in the depth of the water. All samples that were anal 
yzed .were secured at depths ranging from 25 to 65°, 9 
that this factor was fairly constant. According to the anal- 
yses made at Naples, this element of depth entered very 
strongly into the problem of quantitative distribution, ore 
being a marked decrease in numbers as the depth increas : 
It has already been ascertained through the investigations 
of Frinkel® and Reimers? that virgin soil is much poorer a 
bacterial life than that which has been disturbed, and es 
a general way, the bacterial contents of a soil are large ei 
pendent upon the amount of organic material that 1s ak 
tained therein. As the sea bottom is practically nage 
as far as the influence of man is concerned, a Soot ee 2 
the germ life of different soil bottoms ought to yield na : 
results. 
From a mechanical standpoint, a fine silt would upton ; 
conditions for bacterial life than a coarser soil, = may 
more room in the interspaces in which the bacter! 
velop. “1 sand 
Whitney’ has estimated the absolute empty eae fully $3 
to be 45 per cent. of its volume while that of clay . 
er cent. more. he sea 
: The majority of the samples that were taken pa fine 
bottom were either composed of a very fine at ‘i 
quartz sand mixed with clay. In several instance> 
eiatog call ’ 
of pure ‘“‘live” sand, as these shifting shoals are the analyses 
from we" 
bottom thirty 
according to the physical character of the found that 
the respective samples were derived, it was 
°Frankel: Zeits. f. Hygiene m (1887). 521. 
7Reimers: Zeits. f. Hyg. vir (1889). 307. ae 
*Whitney: Fourth Md. Agric. Rept. (1892). 251. 
