Halsted: Degenerate Plants 



275 



only a very small percentage of the 

 attempted combinations of the Scarlet 

 Runner upon bush snap beans have been 

 successful. It should be stated that 

 only a small percentage of the blooms 

 of a Scarlet Runner inflorescence pro- 

 duce pods and therefore hope still lingers 

 that by multiplying the attempts success 

 may be achieved. 



These hybrids have been in the breed- 

 ing grounds for several years and they 

 follow the general rule of producing in 

 the F2 an extremely wide range of 

 plants. For example, there were dwarfs, 

 some of them so small as to attain only 

 a few inches in height, with the small 

 leaves near each other, and producing 

 no flowers. Other plants went to the 

 opposite extreme in size and spread 

 out in all directions from the tip of a 

 tall pole, abounding in blooms and yet 

 yielding no fruits. During the last 

 season there was a block of a hundred 

 hills of this hybrid and no two plants 

 were alike in all respects. A majority 

 of the set did not produce seed but there 

 were a number in the intermediate 

 class that were fairly prolific. In years 

 past plants of remarkably high produc- 

 tive power have been selected and con- 

 tinued through some generations with 

 the prolificness unimpaired. From all 

 the light that has been thrown upon the 

 subject by long association with these 

 hybrids it seems probable that the factor 

 for seed-production will be inherited 

 with some degree of uniformity where 

 the plants are left to their own devices. 



Again, it is noted that a union made 

 between two species is followed by the 

 production of a set of offspring a num- 

 ber of which answer to the general mean- 

 ing of degenerates, and, furthermore, 

 these deficient plants are of two opposite 

 and extreme types, namely, those of 

 feeble growth and unusually weak in 

 reproductive power, and, secondly, the 

 giants of the cross that while surcharged 

 with vigor as expressed in unlimited 

 growth are barren or nearly so. 



WEAKNESS OF SWEET CORN 



The above instances do not by any 

 means exhaust the list of defective 

 plants that have come from the work 

 in breeding. In fact, a large part of the 



researches has been with crosses of 

 plants that already have a weakness 

 and in so far are degenerates. A most 

 familiar instance is the sweet corn. 

 Here the mother plant lacked the active 

 factor of storing an ample supply of 

 starch in the maturing kernel and the 

 offspring must do as best it can with the 

 sugary content of the grain. It is a 

 well-understood fact that such shriveled 

 corn is comparatively low in viability, 

 and when the soil is damp and cold 

 may fail to produce plants where the 

 common type of grain thrives. When 

 the two last named types of corn are 

 bred together there is frequently a large 

 percentage of the Fi plants that are 

 albinos and therefore fail to mature. 

 The same is true of the crosses of the 

 Cuzco with our largest types of field 

 corn, and further, it was found that the 

 plants, while as a rule of strikingly large 

 size, were entirely unprofitable for crop- 

 production. This albinism may be only 

 partial, the plants outgrowing the weak- 

 ness; and, furthermore, this defect is 

 sometimes racial in corn as for example 

 the variegated kinds that are grown for 

 ornament. A study of these latter 

 kinds leads to the opinion that as a rule 

 they are of low stature and produce few 

 and small ears. It is well to rank such 

 varieties as degenerates, for they pro- 

 duce a large percentage of plants with 

 deficient vigor and it would be a dis- 

 advantage to have them reproducing in a 

 field of normal corn. 



Many variegated ornamental plants 

 are recessive to the solid green or 

 normal chlorophyllous plants. Some 

 breeding work is now in progress with 

 nasturtiums in which it is shown that 

 the varieties with the dark green 

 leaves are dominant in that character 

 over those with pale green foliage, and 

 both of these are dominant when bred 

 with the variegated sorts. In other 

 words, the kinds least fit to use the sun- 

 light in their life processes are recessive. 

 The same rule holds with peppers that 

 have pale green leaves and unripe fruits 

 and no exception, as far as is recalled, has 

 been met with on the breeding grounds. 



In passing it mJght be mentioned that 

 the wrinkled peas are comparable with 

 sweet corn in the failure of the seeds 



