Vol. VIII. No. 186. 



THE AGRICULTURAL NEWS. 



187 



SCIENCE NOTES. 



On the Production of more than one Seedling 

 from a Single Seed of the Orange or Mango. 

 In the RcpDit, ot rhe Florida Experiment Station 

 for I90S, Mr. J. Belling, B.Sc, gives an interesting 

 account of some new work conducted by him on the 

 phenomenon known as polyembryony in the case of 

 certain varieties of orange and mango, more pai'ticu- 

 larl}^ of mango. 



Briefly, the facts implied by tlii.s "term are as follows. 

 When the .seeds of such varieties of mango and orange are 

 planted, it is found that more than one seedling will develop 

 from each seed, as many as nine being sometimes formed. 

 ^Moreover, there is a further fact of considerable interest in 

 connexion witli the yonng plants .so obtained. Where the 

 .seed has been produced by crossing two varieties of orange, 

 it is often found that only one seedling .shows any characters 

 in conunnn with the paternal parent, while all the others 

 resemble the ninther plant only. Or it may even happen 

 that all the seedlings resemble the maternal parent only. 

 'J'hus one true hybrid alone can be formed. As will be 

 explained later, this has an important Ijearing on the produc- 

 tion of plants of good varieties from seed rather than by 

 budding. 



For a coniiilete understanding of the (juestion, a slight 

 Icnowledge of the general structure of the ovule or unfertil- 

 ized seerl is necessary. 



The young seed before fertilization con.sists of a small 

 more or less egg-shaped lump of tissue, known as the iiiirelluK, 

 Avhich is borne on a short stalk, and by which it is attached 

 to the ovary wall, and completely surrounded by two coats, 

 known as the inner and outer iiiter/imientx respectively. ' The 

 integuments almost entirely cover the niicellus leaving only 

 a. small hole at the end opposite the stalk. This hole is 

 known as the micropyle, and through it the long pollen tube, 

 which grows out from the pollen grain, is able to enter the 

 ovule for purposes of fej-tilization. 



In the centre of the nucollus is a large cell or hollow 

 known as the embryo-sac, wliich rontairis the female cell or 

 ovum. 



The whole is enclosed in a capsule of soft green tissue 

 knovi'n as the ovary, which may contain one or many seeds. 

 The pollen tube alreaoly referred to, grows out from the pollen 

 grain, passes down the style of the fen'iale flower through the 

 wall of the o\ary, and into the micropyle. Finally it grows 

 through the tissue of the nucellus and enters the emljryo-sac. 

 I'he male cell passes down -this tube and fuses with the egg 

 cell or ovum in.side the embryo-sac. "'' 



The ertects of this fusion are twufold. First, it causes 

 the fertilized female cell to divide and grow, so that it forms 

 the embryo, and eventually the young plant ; and secondly, it 

 gives a general stimulus to the ovary and ovide, causing them 

 to develop into the fruit and seed. This is tlie course of 

 events in the normal case. 



In the abnormal case considered in this article, as 

 presented by the orange and mango, the additional or adven- 

 titious embryos develop from certain cells of the nucellus 

 bordering on the embryo-sac near the micropylar end. They 

 appear to develop as a result of the .stimulus of fertilization 

 in most cases, but the male generati^-e cell takes no part 

 Avhatever in their formation. They simply arise by the 

 gi-owth of one cell of the mother plant and are com[)aralde 

 with any other method of vegetative Teproduction, such as 

 the formation of suckers or the gro^\ th of cuttings, or buds. 



The male ]iarent has absolutely no direct part in their 

 growtli. Conse()uently one. would expect that such seedling.s 

 formed from the nucellus of the female parent would breed 

 true to that parent and carry on its characters with the 

 minimum of variation. In other word.s, .such adventitious 

 seedlings should behave exactly like buds or grafts, and, in 

 gardening [larlance, ' breed true.' 



Curators of Botanic Stations and others interested in 

 general questions of agriculture might find it of interest to 

 investigate what West Indian varieties of mango and orange 

 will produce adventitious embryos and which will not. This 

 could easily be done by sowing some oO or 100 .seeds of each 

 of several varieties, and observing if any seed gave more than 

 one seedling ; and if so. how many more. The seeds nntst of 

 course be sown separately. 



For those interested in more advanced work, one or two 

 other points present themselves. 



It would be of interest to determine if the adventitious 

 embryos can ahvays be relied upon to breed true. This might 

 be determined by planting .some twenty-five seeds of a known 

 variety of orange or mango and taking careful notes of the num- 

 ber of seedlings arising from each seed and th.e general appear- 

 ance of the young jjlants, and comparing them with the 

 parent. The plants might be kept until the fruit formed, and 

 this might al.so be compared with the parerit. It must ahvavs 

 be borne in mind, however, that one seedling is normal in anv 

 group arising from one seed, and consequently will not ■ lirecd 

 true. ' If only one seedling is produced from each seed it will 

 be the normal one, and it is useless to proceed with the 

 experiment on such a variety. 



Having determined that the seedlings of a gi\en variety 

 breed true, further experiments might be undertaken to 

 determine if it is cheaper to rear such a variety from seed or 

 by budding. 



It would also be of interest to determine by emascula- 

 tion, if any varieties of mango, such as No. 11, as suggested 

 by Mr. Belling, will produce adventitious embryos, without 

 being fertilized at all, or if the stimulus of fertilization is 

 necessary to incite their growth. This is suggested by the 

 fact that in certain vaiicties adventitious embiyos alone are 

 formed, the hybrid failing to appear altogether vvhen the 

 seeds terminate. 



RICE IN BRITISH GUIANA. 



The fortnightly rice report, dated Jlay 28 last, of 

 Messrs. Sandbach, Parker, & Co., of Georgetown, 

 contains the following : — 



The weather during the fortnight has not been very 

 favourable for milling, though suttieiently dry to allow of 

 a moderate quantity of rice being cleaned and shipped to 

 town. .Several days of heavy rain were exjierienced during 

 this and last week. These were needed to allow of the 

 October to December rice crop being planted, and to establish 

 j'oung cultivations, and laViourers are busy in all districts, 

 getting plants into the fields that have been already ploughed. 



Prices are the same as last advised, viz., §4'30 to S4"40 

 per bag of 1 80 lb. gross. 



Stocks are not very large, and we exijcct t.i see better 

 prices shortly, as with the wet season now on, and the 

 consequent small deliveriL'S to tovim during the next few 

 months, there .should be a better local demand. 



Shipments to the West Indian islands during the fort- 

 night amount to about l',800 bags, principally for Barbado.s 

 and Trinidad. 



