6go 



Journal of A<^rkuUurL\ Victoria. [ii Nov., 1912. 



fire. The percentage germinations are high, beeanse as soon as the 

 seed becomes permeable in the eonrse of time and swells, it either 

 germinates or dies, so that in the deeper layers the only seeds found 

 are likely to be hard macrobiotic ones. In fact, all the seeds found 

 in the soil below the surface needed treatment with sulphuric acid 

 to produce swelling and germination. Once they are swollen, the 

 seeds are incapable of remaining long living in a latent condition 

 without germinating, and this applies generally to the seeds of 

 Leguminosa\ whether cuticularized or not. 



Acacia dealbaia 



leprosa . . 

 melanoiri/lon. 



lonrjifolia 



Vaf. mucronata 



verlirilln/a 



Depth. 



(i 

 fl 



12 



18 

 4 

 8 



12 

 I) 



12 

 4 

 8 



12 

 (i 



l(i 

 4 

 8 



12 



Seeds 



Present in 



Eiglit Cubic 



Inches. 



28 

 17 

 Hi 

 1 1 

 3 

 1 



28 

 15 

 11 





 32 



Xunilter 

 Gerniinable. 



2() 

 13 

 10 

 !l 

 3 

 1 

 2 





 24 

 14 

 10 



4 



Per Cent. 



03 



77 



03 



82 



1 00 



1 00 



100 







86 



93 



91 



80 



100 



100 







81 



8(J 



100 



Hence it is not surprising to find that it has been found possible 

 to establish a breakwind of acacias on land where they had previously 

 grown by merely fencing off a broad strip of land, letting a fire run 

 over the surface and then ploughing. Sufficient seed was present in 

 the surface soil to germinate under this treatment and establish a 

 good wind-break of acacias without any planting or seeding being 

 necessary. It will, of course, only succeed on ground where acacias 

 were formerly abundant, and the interval of time since acacias were 

 originally present must not be too great, probably not much more than 

 fifty years or so. 



On new ground, acacias can only be established either by planting 

 or sowing seed. Every sample of acacia seed will contain a variable 

 percentage of hard seed according to the conditions under which the 

 seed ripens, and occasionally all, or nearly all, the seed in a particular 

 sample may he hard. This hardness is due to the impregnation of 

 tlie outer skin, either the cuticle or also part of the epidermal layers, 

 with a waxy substance, making the seed impermeable to M'ater."^ If 

 a little nick is made in the skin with a file, water enters the seed at 

 this point, making it begin to swell and separating the particles in 

 the wax layer, so that the whole seed is able to absorb water and swell. 



