280 BOTANICAL GAZETTE [APRIL 
It appears, then, that for this biological group, which includes 
a number of plants for the most part unrelated systematically, no 
general rule can be formulated regarding leaf absorption. The 
experiments go: to show that Holacantha and Koerberlinia hardly 
absorb at all, while Fouquieria is certainly capable of absorbing 
considerable quantities of water. 
GROUP IV. 
The only representatives of the cacti that have been studied 
thus far are two species of Opuntia, O. Engelmanni and O. ver- 
sicolor, A number of specimens of each species were selected after 
a prolonged drouth, the results of which were plainly seen in their 
much shrunken condition, very favorable, it would seem, for the 
demonstration of absorption if this ever takes place. As the mate- 
rial was rather bulky the large balances were employed, a terminal 
joint in each case being severed and weighed; but there is no reason 
to doubt the substantial accuracy of the results. 
As shown by Tables XII and XIII, Opuntia Engelmanni did 
not in any case gain more than 0.6 per cent. of its original weight, 
even when immersed in water upwards of 45 hours, and it is safe 
to conclude from this result, drawn from experiments with a num- 
ber of specimens, that the species in question does not normally 
absorb any considerable quantity of water in this way. Opuntia 
versicolor, on the other hand, treated in the same manner, showed 
TABLE XII. 
OPUNTIA ENGELMANNI. December 1904. 
No.| Date Time Weight in| pe st ocieed Conditions 
1 | Dec. 3 | 10:15 A.M. | 82.360 In each case gain followed wetting 
ad loss followed drying rs, = 
oan indicated a the 
1:30 P.M. | 82.850] 0.6 gain 
§.| 18:00 A.M. | 83: 360] 0.6 
2 6 | 10:12 A.M. | 72.085 
I:10 P.M. | 72.470] 0.5 gain 
3:05 72.080] 0.5 loss 
3 10:39 A.M. |131.750 
1:33 P.M. |132.290) 0.4 gain 
3:20 131.760] 0.4 loss 
