for December, 1920 



403 



fully bred varieties and should contain in the protoplasm of its 

 ernliryo potentialities for producing the highest possibilities of its 

 kind. 



During recent years commercial seed growing has assumed 

 large proportions and has become almost strictlj' localized; 

 that is, the growing of certain kinds of seeds is confined to 

 one or two localities. This selection of localities does not ap- 

 pear, however, to have been as a whole brought about because 

 of any advantages the region may possess w'ith respect to the 

 maintenance or development of desirable hereditary quahties, 

 but more because of cheapness of production in that locality and 

 the effects of the conditions upon maturity and curing. 



Perhaps the most striking instance of localization is that of 

 the Santa Clara Valley, Cahfornia. This region has a great 

 reputation for seed-growing mainly because of the relative cer- 

 tainty in the prevalence of uninterrupted dry conditions during 

 the period covering the maturing and the harvesting of seeds. 

 Among numerous other kinds, many hundreds of acres of sweet- 

 peas are grown for seed in California ; but the question arises 

 as to whether that locality does or does not produce the best 

 possible seeds for out-door work in the Northeastern States ? 

 Judged by all factors of plant physioIog>- relating to the de- 

 velopment of desirable hereditary qualities, it would appear that 

 the climate of the above region is not the most suitable for the 

 purpose, because it may in general be taken as a physiological 

 fact that seed should be groicn under as >iear as possible the same 

 environment as the crop grown from it will have to occupy. 



Further, many gardeners have been for some years of the 

 opinion that there has been a marked cliange for the worse in 

 the results from some seeds continually produced in California, 

 especially has this been so in connection with the onion and 

 radish, the former showing considerable deterioration in its keep- 

 ing qualities. 



Attention has been previously called to the fact that seeds 

 inherit the constitution and characters of their parents, it there- 

 fore follows as a matter of course that seeds from plants grown 

 in a particular environment will themselves produce plants more 

 suited to a similar environment, and less suited to a more or less 

 opposite environment elsewhere. It is a well known fact that the 

 same variety of corn grown in the South and sown side by side 

 in the North with the same variety from seed produced in the 

 latter district, will mature very much later, even if it matures 

 at all. 



The advisability of gardeners producing their own seeds has 

 frequently been considered. In a general way this is scarcely 

 worth while, and is in the majority of gardens impracticable 

 under proper methods. There is. however, little doubt that the 

 growing of purer and better strains of the kinds best suited to 

 one's own local conditions and environment maj- be made of great 

 practical value by those having sufficient room and who under- 

 stand the principles of plant breeding and seed selection. 



.\ not uncommon practice is to save seed from "left-overs,'' or 

 from plants that have run to seed more or less prematurely, and 

 which are useless for table purposes. The only result of this 

 method is to deteriorate the quality of the strain, and, if con- 

 tinued over a series of years, to produce worthless varieties. 



In saving seed it is of the first importance to have clearly in 

 mind what are the ideal characters of the plant from which 

 seed is required, and out of the plants one has, to select the 

 best or those which approach the ideal the most closely. 



A row of spinach sooner or later runs to seed and is of no 

 further use; but it frequently happens that there are one or more 

 plants in a row which do not commence to throw up flower heads 

 until some time after the others. If these latter are allowed 

 to remain for seed while pulling up all the rest, w^e shall be 

 saving seed from those standing the longest, which is what is 

 re<|uired of spinach. From this stock-seed more seed can be 

 produced and if selection of the longest-standing plants is again 

 carried out and continued year after year the long-standing char- 

 acteristic of the strain will become more pronounced as years 

 go by. This same principle can be applied to any plants grown 

 from seed in connection with any special characteristic which 

 makes particular individuals stand out as being better than others, 

 and in all cases seed should only be saved from the best, and in 

 some cases the best one has are not good enough to save seed 

 from. 



The fact that all cultivated plants have had wild ancestors has 

 been previously alluded to, and with some exceptions the wild 

 types are still to be found although they have been domesticated 

 since before the dawn of history. However long the period 

 durinc which cultivation and selection has been going on, plants 

 today have retained in their cell protoplasm, potentially or actively, 

 the specific characters of tlie respective types from' which they 

 have sprung. 



Some thirty or more years ago Weismann brought out very 

 clearly the fact of the continuity of the germ plasm. By saving 

 seed from plants with more pronounced features in certain desir- 

 able directions, and at the same time by giving these plants more 



food and other things calculated to improve them, undesirable 

 cliaracters l;ecomc suppressed by better ones. It must be re- 

 membered that before any visible betterment of the constitutional 

 characters of the growing plant can be obtained, such betterment 

 must be produced in tlie protoplasm of the cells, and there is more 

 or lejs a kind of competition going on in the cells between what 

 may be called the germs of good and bad characters. It is only 

 by constant selection and attention to breeding from the best that 

 bad characters are kept suppressed and good ones strengthened. 

 .As it is, "throw-backs'" are common and the elimination, or 

 "roguing" of these is one of the necessary and continual oper- 

 ations of high class seed production. 



The acquired characters of cultivated plants do not cause any 

 fundamental or specific change in the germ-plasm; it is therefore 

 very easy by want of care in seed growing, coupled with poor 

 environment, for seed stocks to run down, and in some cases, as 

 pansies for e.xample, they will revert to their wild types in a 

 few years. 



Improved varieties of fruit and other trees are sometimes the 

 result of bud variation or "sports" which have been propagated 

 by vegetative process, such as grafting, (to be more fully dis- 

 cussed later ) and not by seed. Plants from seeds of apples, etc., 

 invariably produce fruit little, if any, better than the original wild 

 type, although it does happen, perhaps once in many thousands 

 of tiiries, that a variety arises from seed that is worth wdiile cul- 

 tivating. 



This reversion to the original wild type is equally as possible 

 among animals. 



Our improved varieties of domesticated animals are, as with 

 plants, the result of the combined influences of selection and 

 of better environment, and a discontinuance of these influences 

 would sooner or later result in the production of comparatively 

 useless mongrels and a complete reversion to their originals. 

 Darwin emphasized this when he pointed out that if specimens 

 of all the varities of domesticated pigeons were together turned 

 loose upon an island far aw-ay from any other land and the 

 incursions of other pigeons, they would in a few years revert 

 to the wild Blue Rock Pigeon from which the various kinds of 

 domestic pigeons have been selected and bred. A very striking 

 assertion which is really a proof of the impossibility of the origin 

 of species by natural selection. 



The improvement of plants and the production of new varieties 

 by hybridizing is quite a different proposition from selection alone. 

 Strictly speaking a hybrid is the result of the interbreeding of 

 two difi^erent species. The term is, however, frequently used in 

 a broader sense as covering the offspring of a cross between two 

 distinct plants, whether they are merely different varieties of the 

 same species or belonging to difl^erent species. 



The tendency of systematic botanists is to multiply both genera 

 and species. Were the zoologist to adopt the same methods as 

 the botanist, he would class the pnny, woolly Shetland pony as 

 a different species to the .\rab horse, whereas there is no specific 

 difference between them as they are merely two varieties which 

 have resulted mainly from living under e.xtreme differences of 

 environment for many thousands of years. 



It almost goes without saying that some species are more 

 closely allied than are others in the same genus. The closer the 

 alliance lietween two distinct plants the easier is it to produce 

 hybrids from them ; and even when hybrids are produced they 

 themselves are often sterile and in this case the hybrid cannot 

 be propagate<l from seed. The further apart two species stand 

 in relationship lo each other the greater is the likelihood of a 

 hybrid from them being sterile. 



The same thing occurs in animals. Hybridizing the horse and 

 the ass results in the mule which is always sterile; this is another 

 fact disproving the Darwinian theory of the origin of species. 

 With plants, however, we have the before mentioned method of 

 vegetative propagation whereby sterile hybrids may be increased. 



The method of artificially hybridizing plants is to remove the 

 stamens before the pollen is formed from the flower of one, 

 (emasculation) ; and when the pi.stil of that flower is mature, 

 convey to it the pollen from a flower of another plant, the charac- 

 ter of which it is desired to incorporate witli the other. The 

 flower of the plant it is intended to pollenize must be continually 

 kept covered with a bag so as to prevent insects or wind convey- 

 ing undcsired pollen to it. 



It is not always that the combination of characters desired 

 from hybridization appears in the first generation, in fact it may 

 be taken as a general rule that one must wait until the second 

 generation before the expected result will appear. In times gone 

 by hybridizing was conducted more or less in a haphazard manner, 

 but the researches and experiments of Mendel. De Vries, Correns, 

 and many other investigators, have to a certain degree developed 

 a science of heredity upon the principle of wdiich more exact 

 hybridization has been based to an extent which twenty years ago 

 there was no conception. The principles underlying scientific 

 plant-hybridization have received the generic term Mcndelism. 

 (Continued on page 406) 



