TxKi.rKNci: <>k Fohksts on Natuhak Wa rKi;-.Sur'PLV. 121 



springs or wells. Near Pretoria, a \aliiablt> ptMiiiaiKMit sjiriiig lias 

 completely dried up since the growth of a large plantation oi eucalypts 

 on the mountain slope just above it, and another spring has been 

 steadily diminishing since the planting of similar trees on another 

 part of the sanie farm. The water-suj)ply in the well at the biick- 

 rields at (Jroenkloof, within the municipality of Pretoi'ia, has fallen otl' 

 considerably since the eucalyptus j)lantation alongside of them was 

 started. It is well known that, since the introduction of eucalypts 

 into Italy in 1869, the swamps on the Campagna have been largely 

 dried up bv the action i»f these trees, and similar results liave been 

 obtained in the swamp}' ground near the Royal Observatory at Cape- 

 town. This effect of eucalyptus forests seems to be beyond (ju^^stion. 

 In a paper read before the Royal Society of New South Wales, in 

 1880, Mr. "W. K. Abbott refers to the result of ring-barking forests of 

 eucalypts in the Hunter River district, and mentions three creeks 

 which were dry e.xcepting after unusual rainfall, but became perma- 

 nent running streams after the ring-barking had been done. As 

 pointed out in the paper refei-red to, the eucalyptus has obtained the 

 reputation of being possessed of exceptional capabilities for absorbing 

 water, and it has been successfully used as a means of draining swampy 

 groujid. These capabilities of absorbing moisture are strikingly shown 

 by the gaugings which Mr. Abbott made of the supply in the creeks 

 mentioned. Similar action was taken in the catchment area of the 

 ^lundaring dam of the Coolgardie Waterworks, where some 20,000 

 acres of the lower ax'ea were ring-barked so as to increase the intiow.* 

 It is one of the characteristics of the genus that the leaves are often 

 st<)matiferous on both sides, and in the intensity of aqueous exhalation 

 many eucalypts vastly surpass elms, oaks, poplars and various other 

 trees. The power of E. amygdafina to absorb moisture from the 

 ground is enormous. On the leaves of E. hfihrhina 91,000 stomata 

 per square inch have been found on the upper surface, and 104.000 

 on tlie lower E. cornntn is credited with 83,000 and 120,000 re- 

 spectively, and on the leaves of E. ki.rfoiikina 33,000 to 43,000 have 

 been found on the upper surface, and from 9"), 000 to ltj6,00*> on the 

 lower, t 



The same effect takes place with the rapid-growing acacias. TJiere 

 is a case in Natal where ten years ago a stream fed a hydraulic ram, 

 but the rtow ceased in consequence of planting the drainage area with 

 black wattles {A. decurrens, rar. moll la.).! Recently the wattles have 

 been cut down and tlie spi-ing has revived. The author knows several 

 places in the Transvaal where springs have been seriously affected since 

 the planting of this species or of silver rattles {A. di'currens, car. 

 deidhata). In some cases the springs ha\e completel}' dried up, while 



" M'nnitis itf Prori-edhif/s of ItistUiififD) nf Ciril Eiif/liim:s, vol. olxii, p. 64. 

 t EncalnptH of Australia, by Baron F. v. Mueller, F.ll.S., &c., «!ve., who 

 suggests that the <Iifl"ereiice in the latter case may be <hie to a^e of tree^;. 

 i These were fonueily jilanted umler the )i;inie of A. itadlixtiihio. 



