640 



FARMERS' REGISTER. 



No. 9 



offices these organs perform, the manner in which 

 they perform these offices, and the changes which 

 they naturally undergo, or which they may be 

 made to undergo by the art of man. Its object is to 

 Jay open the machinery of vegetable lile, and to ex- 

 plain the manner in which that machinery operates. 

 In order the more distinctly to illustrate the applica- 

 tion of such knowledge to practical agriculture, I 

 will select that which concerns one subject ; viz : 

 the circulation of the sap. We all know thai 

 plants are nourished by their sap, just as animals 

 are by the blood which circulates through their 

 veins. 



If we inquire for the point at which the sap en- 

 ters a plant, we find it to be the root, but not all 

 parts of the root alike. There is a peculiar class 

 of organs whose office it is to absorb nourishment 

 from the soil ; and these are situated along the 

 fibres or smaller subdivisions of the root, of course 

 it is at these points and no others that the sap en- 

 ters. Let us see if we can make any practical 

 application of this knowledge. If we wish by 

 manuring to assist the growth of a tree, we should 

 place the manure at some distance li-om the point 

 at which the trunk enters the ground, so that it 

 may He as nearly as possible over the fibres of the 

 root. If we wish to plant a vine so as to twine 

 around a tree and be supported by it, we should 

 plant it very near to the point at which that tree 

 enters the ground, rather than at the distance of 

 several feet from it ; because in this way the two 

 will interfere least with each others growth. If we 

 wish to transplant a tree we should be more care- 

 ful about the extremities, than about the main di- 

 visions of the root. If the root have several 

 branches, it is better to cut ofT all those branches 

 excepting one and retain that with all its subdivi- 

 sions perfect, than to cut ofi' the ends of all the 

 branches, as is the common practice. 



Again ; if we trace the course of the sap dur- 

 ing the different seasons of the year, we find that 

 in such trees as the oak, the hickory and the chest- 

 nut, it circulates principally in the sapwood during 

 the spring and summer, but during the autumn 

 and winter it retires to the heart-wood and not to 

 the root, as is generally supposed. In order to 

 satisfy ourselves of this, nothing more is necessa- 

 ry than to take a part of the body of a small tree 

 cut in the spring, and of another cut in the winter, 

 and lay them on the fire. The vsap will be seen 

 to exude in the first from near the surface ; in the 

 second from the heart. Let us see if we can make 

 any practical application of this knowledge. It is 

 generally acknowledged that, that most destruc- 

 tive disease in timber called the dry-rot arises from 

 the presence of the sap. It is generally the heart- 

 wood which we use for timber, whilst the sap- 

 wood is considered of little value. If ihen the 

 situation of the sap at different seasons is such as 

 I have just mentioned, in order to get our timber 

 fi-ee from the sap, we should cut it in the summer 

 and not in the winter. The course thus indicated 

 is, I know, in direct opposition to the common 

 practice of^ men. As this is a matter of some 

 practical importance, permit me to cite one fact in 

 confirmation of the rule which I have laid down. 

 The fact is mentioned in connexion with many 

 others of a similar character, in a communication 

 from a very intelligent ship-carpenter to one of 

 our scientific periodicals. " In accordance with 

 the common practice of ship-carpenters I was in 



the habit of cutting my timber in the winter. Du- 

 ring the summer of 1820, when engaged in fram- 

 ing a vessel, I found I had no piece which was 

 suitable for a certain place in the frame. It was 

 necessary that the work should go on, and as the 

 only alternative left me, I sent immediately to the 

 woods and had a suitable slick cut ; this I framed 

 in with the others. After several years the vessel 

 was sent back to me to be repaired. On examin- 

 ing her side timbers, I found them all more or less 

 afiected with the rot, excepting this one, whilst it 

 was perfectly sound. " 



Again ; it' we inquire into the nature of the 

 sap, we find that as it enters the vegetable sys- 

 tem, it consists mainly of water holding carbonic 

 acid gas in solution. Water has the power of ab- 

 sorbing large quantities of certain gases, whene- 

 ver it is brought in contact with them. Strange 

 as it may seem to those who have never thought 

 much on the subject, water is porous, and absorbs 

 these gases just as a sponge absorbs water. 

 The great object of manuring, in most instances, 

 is to supply carbonic acid gas to the growing 

 plant. A large portion of this gas is liberated 

 from vegetable matter during its decay; and hence 

 the value of such matter as manure. The gas 

 furnished by the manure, must be absorbed by the 

 water, as it sinks down into the ground. Of 

 course, the water should meet the manure before 

 reaching the roots, and not atler it has passed be- 

 yond them. This would suggest that the manure 

 could be placed to the best advantage upon the 

 surface, because then the water must pass through 

 it before meeting with any of the roots. But, 

 then, there is a difficulty arising from another 

 source. The valuable material furnished by the 

 manure, is furnished in the form of a gas. If the 

 manure is placed upon the surface, it soon dries, 

 and whilst in that state, as the gas is liberated, no 

 water being present to absorb it, it is soon dissi- 

 pated in the atmosphere. The two facts taken in 

 connexion, suggest that the manure should be 

 placed as near the surface as is consistent with its 

 being kept in a moist state, and in every instance, 

 above the roots of the plant which it is intended 

 to benefit. Where manure is spread upon the 

 ground in the fall to benefit a winter crop, it 

 should be placed very near to, if not upon the sur- 

 face; where it is spread in the spring or early pari 

 of the summer it should be always covered with 

 earth. 



Our knowledge of the nature of sap, enables us 

 to explain the manner in which clover improves 

 land. Had we no experience on the subject, it 

 would seem, to say the least, improbable that any 

 crop could improve land. We would naturally 

 suppose that plants were nourished by the ground 

 itself — that they fed upon the soil. If such be the 

 case, when a crop is ploughed under and decays, 

 it can give nothing but what it has first taken; 

 and how then can it improve land? Yet we find 

 that growing clover upon land, and then plough- 

 ing it under and sufiisring it to decay, is one of the 

 very best methods of improving land. Bearing 

 in mind the nature of the food of plants, this ad- 

 mits of a simple explanation. We will suppose 

 that clover is sown upon a perfectly barren spot. 

 The atmosphere which is above this spot, con- 

 tains a portion of carbonic acid gas, for all atmo- 

 spheric air contains a greater or less portion of it. 

 A rain comes; as the rain falls, it absorbs a por- 



