18 The Philippine Journal of Science 
Table XL — Summary of Tables 9 and 10. 
Position of plant duringr growth. 
Average growth, in 
cm, of plants in 
water through 
which — 
CO 2 was 
passed. 
CO 2 was 
not 
passed. 
Cm, 
Cm. 
Rooted in soil . .. .. „ . .. .. , 
13.2 
3.1 
Anchored over soil _ _ 
13.8 
5.1 
Rooted in sand . .... _ . 
14.0 
3.1 
j Anchored over sand . . ... 
14.3 
5.1 
An examination of Table IX shows that there was very little 
difference between the plants in any of the jars through which 
CO2 was passed. The floating plants averaged a little greater 
growth than the rooted ones, but the difference may well be 
within the limits of experimental error. It is to be noted that 
the roots of the rooted plants developed an abundant growth of 
root hairs while these were entirely absent in the case of the 
floating plants. The surface of the root system of the rooted 
plants was therefore many times greater than that of the floating 
ones. Since, however, the floating plants grew slightly better 
than the rooted ones it would seem that under the conditions of 
this experiment the rooted condition was of no advantage to 
the plants, while this experiment, together with those previously 
described, would appear to show that the function of absorption 
can be performed by the leaves or stems independently of the 
roots. 
Very few roots were developed on the plants in the jars through 
which CO2 was not passed. The results given in Table X show 
that in these jars there was very little difference between the 
plants over the substratums of sand and soil. The floating 
plants, however, showed a considerably greater growth than did 
those held against the substratum. This may readily be ex- 
plained as due to the floating plants being nearer to the air which 
was the only source of COo. 
Table XI shows that while there was very little difference 
between the rate of growth of the plants in any of the jars 
through which COj was passed that all of these plants made a 
very much greater growth than any of those in the jars through 
which CO2 was not passed. The growth of the latter plants 
was, moreover, very spindling, and the increase in length was 
not as rapid as the death at the cut ends. These plants were, 
therefore, actually shorter at the end than at the beginning 
