Improvement of Soils hy Pulverisation. 383 



is possible in either case separately, it is equally possible if the 

 bud be considered as proceeding from the juices without and 

 within, or even from the very substance of the cellular partitions. 

 But it is certain that the sap is not modified (as M. Leclerc sup- 

 poses) by passing from the cells of one wood into those of the 

 other ; on the contrary, it conforms itself in all usual cases of 

 insertion to the nature of the wood through which it last passes, 

 so as to produce that wood unchanged in its growth and progress. 

 M}' reason for giving credit to M. Adam's assertion with respect 

 to the origin of this curious plant is, that we have had no in- 

 stance of a hybrid from seed resolving itself in the course of its 

 growth into its component and fertile elements, nor of any mule, 

 either animal or vegetable, becoming (either altogether or in 

 part) more like one of its parents than it was in the form first 

 assumed after its perfect developement. 

 London, May 29. 1840. 



Art. IV. On 'pulverising Soils, as a Means of improving them. 

 By John Fish. 



The fertility of adhesive soils becomes greatly increased by 

 frequently exposing them to the atmosphere, by which means 

 they become so much pulverised, as to encourage the growth of 

 the fibres of plants. One cause of the unproductiveness of ad- 

 hesive soils is, that air cannot penetrate to the seeds or roots of 

 plants ; preventing the germination of the former, and the future 

 wellbeing of the other. In such cases, the roots of plants can 

 receive no advantage from the carbonaceous matter which exists 

 in the atmosphere, from the decomposition of animal and vege- 

 table substances on the earth's surface. Another cause of unpro- 

 ductiveness is, that such soils cannot retain a sufficient quantity 

 of moisture, but are saturated upon the surface at one time, and 

 burnt as hard as a brick at another. 



In the former case, the fibres of plants are generally rotted, 

 whilst in the latter they are torn in pieces by the cracks in the 

 ground. The moisture will neither sink freely, nor rise freely, 

 when the sun has evaporated the moisture on the surface. Again, 

 in such soils the full advantage of manure cannot be realised, 

 as it must be within the reach of the atmosphere before those 

 changes can be effected, by which alone it can become the 

 nourishment of plants. Hence the importance of trenching, 

 ridging, and frequent digging, by which a large portion of the 

 soil is exposed to the atmosphere, and rendered more friable and 

 open in its texture. These operations may be performed as soon 

 as the ground is clean. The depth will depend upon the nature 

 of the soil and subsoil : strong soils can scarcely be dug or 



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