JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 



[ March 17, 1S70. 



penBe of the fruits, little pruning will be required. The points of 

 the young growing s hoots may be pinched out in summer. Cat 

 out the shoots altogether when they become too crowded, and lay 

 the others in at full length, excepting where it is necessary to 

 prune back to secure a fresh supply of young shoots from the 

 lower part ; and this must be Btrictly attended to, to prevent 

 the trees from extending beyond bounds, and having the fruit- 

 ing shoots only at quite the extremities, the centre and lower 

 part altogether being bare and unfruitful. 



Titi-s under Glass. — The best form for these when planted 

 out where Bpace can be afforded is the same as that recom- 

 mended and generally adopted with trees on walls ; and in 

 respect to pruning much the same practice must be followed, 

 a little more allowance being made for the improved position 

 and better-ripened wood of those under glass. Another form 

 is that of the bush or half-standard, but such trees when 

 planted out are extremely apt to grow too luxuriantly, and in 

 consequence become unfruitful. The shoots should be kept 

 very thin, bo as to obtain all the sun's influence possible to 

 thoroughly ripen the wood, and in the summer the young 

 growing shoots should be vigorously pinched, in order to check 

 luxuriance and bring the tree into a stubby fruitful form of 

 growth. In general, as to training, pruning. &a., the treat- 

 ment will be the same as that about to be fully explained for 

 trees in pots. — A. B. C. 



HYBRIDISING PELARGONIUMS. 



One of the most important matters in connection with hybrid- 

 ising, as in almost all undertakings, is to hit upon some definite 

 standard, so that the operator may have some decided object 

 in view. By this course the operator will be far more likely 

 to arrive at some satisfactory result than by merely trusting 

 to the chance of getting something good. It is a common 

 but delusive idea that two varieties, being distinct, will be 

 sure, when crossed, to produce something different from either 

 of the originals, though it is just a chance if one of the seedlings 

 so produced will be better than the parents, or even equal to them. 

 Presuming, therefore, that the hybridiser is desirous of obtaining 

 some particular cross with the object of arriving at the result he 

 has set before him, and has fixed upon the varieties which he in- 

 tends using for the purpose, the next important matter is to select 

 good healthy plants as parents on both sides, as without healthy 

 parents you can never expect seedlings from them to be strong 

 and of good constitution ; even though they be the most beauti- 

 fully marked and distinct in flower, they can but be counted 

 second-rate. 



Having, then, made choice of good healthy plants, all the flowers 

 that are expanded upon the plants that are to be used as seed- 

 bearing parents should be taken off, and the plants removed as 

 far from others as possible, or if they can have the house to them- 

 selves so much the better; still, if care be used, this is not abso- 

 lutely necessary. 'Watch the seed-bearing parents closely every 

 day till the first flower opens, and immediately the petals are 

 sufficiently expanded to admit of its being done without injury 

 to the flowers, perform the first operation. The anthers, which 

 are the male organs, appear as little knob-like portions, standing 

 up prominently in the centre of the flower; these must be care- 

 fully taken out, without injury to the centre column or pistil. 

 Always bear in mind that there are, in a perfect Pelargonium 

 flower, also two of these anthers lower down the centre of the 

 flower than the rest, which must also be carefully taken out. 

 This cf.nbe done by a pair of sharp-pointed scissors, or a penknife. 



Having satisfactorily accomplished this operation, watch care- 

 fully the progress of the female organ of the flower to its matu- 

 rity, which in healthy flowers takes two or three days from the 

 time the flower expands. Double flowers are an exception to 

 this rule, for I find they take twice as long as the single to come 

 to maturity. Last year I had sixteen seeds from Gloire de Nancy 

 and Triumph. 



As I am writing this principally for amateurs, I ought, per- 

 haps, to explain hpre that the female in a Pelargonium is the stiff 

 thread-like portion coming immediately from the centre of the 

 flower (surrounded by the filaments bearing the anthers) and 

 having the appearance, in its earliest stage when the flower first 

 opens, of one single thread-like projection, but which, as it ad- 

 vances to maturity, divides into five distinct parts at the point, 

 each division being the direct channel to a distinct seed-vessel at 

 its base. Now, it is just this period of arriving at perfection in 

 the female organ that is one of the most important matters in 

 hybridising. The best time, in my opinion, and what I generally 

 follow in practice, is to apply the pollen as soon as possible after 



the division of the pistil into its distinct parts takes place, and 

 before it has expanded to its full size. It is not only in its best 

 state then for receiving the pollen, but there is less likelihood of 

 its becoming impregnated with another than that intended. I 

 may add that once impregnated with the one desired, all foreign 

 pollen coming in contact therewith availeth nothing. 



In selecting flowers, choice should bo made of the first eight 

 flowers that open on the truss, for, as a rule, they are the strongest 

 and best. I make it a rule to cut all the others away. — James J. 

 Ckaig. — (Toronto Globe.) 



THE CHEMISTRY OF MANURES. 

 An interesting discussion which took place in the columns 

 of The Journal of Horticulture with regard to manure, and 

 whether it lost any of its value by being spread upon the land, 

 and subjected to the action of sun and air before its being 

 ploughed in, led me to read up again the different authorities 

 on the chemical value of manures, and to examine into the 

 reasons which are adduced for considering nitrogen so impor- 

 tant a part of farmyard manures as to make the whole relative 

 value of a manure depend upon the quantity of nitrogen it 

 contains ; so much so that in the discussion I have alluded to, 

 started, I believe, by Mr. Pearson, of Chilwell, the question 

 turned upon whether there was a loss of nitrogen in the ma- 

 nure or not by the action of the sun and air. Now, I have 

 come to the conclusion that nitrogenous manures as a rule 

 are valuable not on account of the nitrogen they contain, but 

 because all organic compounds which contain nitrogen are 

 easily decomposed, and also because the two principal manures 

 in which nitrogen is present — that is, ammonia and nitrate of 

 soda, are also valuable as solvents for other organic and in- 

 organic elements which are necessary to the life of plants. 



Now, as, I thick, the discussion of this question may interest 

 some of your readers, and as I wish to be set right when my 

 arguments are wrong, I venture to bring forward the reasons 

 why I believe a false and fictitious value has generally been 

 placed upon nitrogen. The argument hinges in the first place 

 upon this very important point, Can plants assimilate nitrogen 

 directly from the air or not? Now, Liebig broadly asserts, 

 " We have not the slightest reason for believing that the 

 nitrogen of the atmosphere takes part in the processes of 

 assimilation of plants and animals " (Liebig's " Organic Che- 

 mistry," page 70), and having made this broad statement, 

 argues from it as an established fact. Professor Johnston 

 modifies this assertion very much and says — " Though the 

 leaves of trees and herbs are continually surrounded by nitro- 

 gen, yet the constitution of plants may be unfitted'for absorb- 

 ing it by their leaves. The nitrogen may not only require to 

 be in a state of combination before it can enter into the circu- 

 lation, but it may aho be capable of gaining admission only 

 by the roots," and afterwards arguing from the value of such 

 manures as ammonia and nitrate of soda, guano, &c, which 

 contain nitrogen, he thinks it proves that they are valuable 

 chiefly because they supply the nitrogen to plants which they 

 cannot get from the atmosphere. Professor Miller in his 

 "Elements of Organic Chemistry," says, " It is generally sup- 

 posed that all the nitrogen found in combination in plants has 

 been obtained either from nitric acid, or from ammonia, or 

 from some azotised compound present in the soil in the form 

 of manure, and that plants have not the power of directly 

 assimilating nitrogen from the atmosphere." He goes on, how- 

 ever to bring several facts which help strongly to question the 

 truth of this theory. 



Why I say the whole subject hinges upon the question, 

 whether plants have power to absorb nitrogen directly from 

 the atmosphere or not? is this, because, as it is well known, 

 nitrogen forms nearly four-fifths of the air we breathe. 



The average composition of the air by accurate analysis in 

 every one hundred parts is — 



Oxygen 20.61 



Nitrogen 77.95 



Carbonic Acid 01.C4 



Aqueous Vapour 1.40 



Ammonia ) 



Nitric Acid \ traces 



Carburetted Hydrogen ) 



100.00 

 Near towns, too, there are other gases to be found, as sul- 

 phuretted hydrogen, sulphurous acid, &«., owing to the quantity 

 of smoke which escapes from factory and other chimneys. Now, 

 as a plant is always living in an atmosphere of nitrogen, if it 



