1366 



TLAXT- BREEDING 



types can be sil..t. d. It is thus important that the 

 hybrids of tin- lusi i;iini:itiun should be inbred with 

 their own pollen or wuli pollen of the hybrids of the 

 same combination, and numerous individuals of the sec- 

 ond generation obtained in which plants showing the 

 desired combination of characters are more likely to 

 be found. 



One of the most prominent characters of crosses is 

 their extreme vigor, which is particularly marked in 

 racial and specific hybrids where the parents are widely 

 distinct in characters (Fig. 1845). In crosses of closely 

 related sorts, which are reproduced by buds, cuttings, 

 slips, etc., and which do not ordinarily remain true to 

 type when propagated by seed, the increase in vigor is 

 not conimoiilv so njarkcd. 



of ai 



secured by sck-L'tion. 



The improvements which < 

 crossing are almost innumerable, and i 

 far as we are informed, fan be secured 

 Such is tin- iini.hl.'lioli (if lrai.'ralit \i\r 

 less tvprs a, Ik,- In, 1, a,-,',„i,|,l,,|,,.,| ,,, 

 sies, an, I lli,> 1,1, 11,111,1; ai,,l .■l,:,ii:,'i 11 - ,,1' 

 and fruits. I ii,T,a-.,',l liai',liii,',-s ami 



1 that all of the hybrids 

 ly sterile, and in most 

 :ertility can probably be 



growtli 111 wariiH-r .lit 

 by simph' s.-l.',-ti..ii th: 

 they can ,I,,ul,tl,ss l„. 

 tender and liar.ly s,>rt 

 obtained which pussess 

 Fixation of Crosses. 



, can oe secureu in no otiier way. 

 ,,f lrai.'ralit ^■a^i,■ti,■s fi-,.ni odor- 



a,-'','ni|,li-li,'l in 11 ■,-,■ ,,f pan- 



ai,,l .■liiiiii.'iii- ,,r .■,i|,,i-s ,,r iliiwers 

 1 liai',lin,',-s an, I a,la|.lal,ility to 

 nates might possibly be secured 

 ■iiugh a long series of years; but 

 most quickly secured by crossing 

 i or species, when plants can be 

 1 these opposite qualities. 

 -In plants which are propagated 

 by vegetative parts no fixation is necessary, but in those 

 which are propagated by seed, all crosses that are 

 found to possess desirable qualities must be fixed by 

 selection into stable races reproducing these qualities 

 true. Usually, a large majority of the progeny of a cross 

 will revert toward one of the parents, Jfnd may not 

 show the characters desired. In order to render the de- 

 sired qualities hereditary, the cross must be inbred 

 with its own pollen or the pollen of another cross of 

 the same parentage which exhibits the same characters, 

 and a large number of plants [;rnwn from the seed thus 

 produced. These plants imivt tl,, 1, 1,,, cnrefully exam- 

 ■ t .: . ! ],rr work which 



ined and indi 



have reproduci-,1 !!,,■ ,1, in the highest 



degree. These in, In i, hi:.! i. 1 _ .1, inbred and the 

 process continue, I r,,rs,v.i,il -, n. im 1, us until all of the 

 plants are reproduced true to tin- desired type. This, 

 in most cases, requires from five to six generations of 

 careful selection. The time used in selecting to fix the 

 type is by no means lost, as meanwhile careful attention 

 can be given to increasing the frnitfulness so that this 

 factor also mav be greatly improved. 



1844. Cotton flov^rers, illustrating the process of emasculation* 



a. niatnrp bnri showiTiff tho stncrn whirh should be 



The Si 1,1. 1 i,,x ,i, \ 1 ,.1: , 1 IN 1: I' m; IS. -Within re- 

 cent years soiiii- aiieninni lias bit 11 fjiieu to the im- 

 provement of plants by the seleetion of buds, cuttings, 

 etc., and the results obtained by certain practical in- 

 vestigators indicate that much may be accomplished in 



PLATANUS 



this way. In orchard fruits, carnations, violets, pota- 

 toes, etc., careful attention should thus be given to the 

 buds ,,!■ ,-uttiiiLs iisiil in propagation. By ;i careful 

 sil,-, 11,111 ,,f vi,,|,t ,iittinj;s from those plants which 

 ■A, r,- 101111,1 to |,r,,ilii, ,■ the greatest number of good 

 il, ■».!>. I'. 11. l)..is,ti lias greatly increased the average 



1845. Increase i 



r. S,-a is 



1 bolls caused by hybridization. 



d as the female parent: H, 



yield of his plants and believes that an increased yield 

 of nearly 100 per cent is perfectly possible by careful 

 attention to this factor alone. Here, again, it is not in- 

 creased yield merely which can be improved, but various 

 other qtialities as well. 



The literature of plant-breeding is mainly scattered 

 through periodicals and is difficult of access. The prin- 

 cipal work treating the subject in a general way is 

 Professor Bailey's "Plant-Breeding" (The Wacniillan 

 Company, New York, 1895). The following are a tew of 

 the most important general papers: "The Production et 

 Fixation des vari^t^s dans les v^g^taux," by E. A. Car- 

 rifere, Paris, 18G5; "Die Pflanzenmischlinge," by W. O. 

 Focke, Berlin, 1881; "A Selection from the Physiologi- 

 cal and Horticultural Papers of Thomas Aiulrew Knight, 

 published in the Transactions of the R,,yal and Horti- 

 cultural Societies," London. Isil; ''ll\l,i-ids and their 

 Utilization in Plant-BreediiiL'." l,\ W , T. Swingle and 

 H. J. Webber; Year-book, T. s. 1 1, |,,,riiii.iit of Agri- 

 culture, 1897; "Sur la Pi-,.,lii,i i,,ii it I;, l'ix.ation des 

 Varietes dans les j'lantcs ,1 ', n 11,1,1, nt," I, \' .lean Bap- 

 tiste Verlot, Paris, Isi;.',; ■■Tli.. I i,,|.r,,N , nnnt „f IMants 

 by Selection," Yearl k. 1. s. 1 1, |,,,i im, ,11 ,.r Agricul- 

 ture, 1898; "Hybrid ( ',.nf, r,ii,e i;,|,.,tt ," .b.iirnal Roy. 

 Hort. Society, vol. xxiv, April, llliMi ; ", Survival of the 

 Unlike," by Bailey. Herbert J. Webber. 



PLANT CELLAKS will be treated under Winter Pro- 



followed b; 



branches during the winter. The smooth, light-colored 

 often almost creamy white bark of the branches and 

 limbs, usually mottled by darker blotches of the older 

 bark, which peels off in large thin plates, gives the 

 tree a very characteristic ap])caranco in winter, while in 

 summer the Planetn,'. willi its large head of dense 

 bright green foliar',' ami \\ itli its massive trunk, is a 

 beautiful and maji^sti,' slia,l, ti-,,. The native i'/a^ainis 

 occidentalis is htirdy m.illi ami /'. orieiilalis hardy as 

 far north as Mass., while the soutlnvestern and Mexican 

 species cannot be cult, in the North. From time imme- 

 morial the Oriental Plane, which was well known to the 

 ancient Greek writers, has been famous for the large 



