DEGENERATE PLANTS 



When Widely Different Varieties or Species Are Crossed, the Extreme Variants 



in the Second Generation Are Frequently Either Dwarfs or Giants, 



and in Both Cases Lack Reproductive Power — Notes 



from the Breeding-Ground 



BvRON D. Halsthd 

 Botanist, State Agricultural Experiment Station, Xe-iv Brunswick , N. J. 



THE term "degenerate" is, of 

 course, one that does not admit 

 of a clean-cut definition, and 

 therefore it is here employed in a 

 somewhat general way for those plants 

 that show some weakness that interferes 

 more or less with their successful struggle 

 for life. 



A gathering up of these notes was 

 suggested by a recent study of results 

 obtained from the breeding of musk- 

 melons and therefore some olDservations 

 drawn from these crosses, with photo- 

 engravings, may serve as more than an 

 introduction. 



The chief combination we have made 

 among the melons has been between a 

 standard type, the Burrell Gem, and a 

 recent novelty of the dwarf group, the 

 Henderson Bush. The cross was se- 

 cured in only one direction, namely, the 

 vine upon the bush, all reciprocal at- 

 tempts being failures otherwise than in 

 emphasizing the fact that breeding is not 

 effected with equal ease in both direc- 

 tions among diverse tyj^es of plants. 



In the Fi there were sufficient plants 

 grown to make it clear that there was no 

 observed effect of the bush u]Jon the 

 offspring so far as size of the jilant is 

 concerned. It is, however, possible that 

 any restraining inflvience of the bush 

 may have been offset by the stimulation 

 that is generally ascribed to a cro.ss in its 

 first generation. 



In the F2 the plants were of the dis- 

 tinct parental types without any ten- 

 dency to produce intermediates; in other 

 words, there was an ex])ression of the 

 Mendelian ratio in the following figures: 

 standards 69.2%, dwarf 30.8%. 



Fig. 11 shows, upon the left hand, a 

 portion of a vine plant coiled upon itself 

 to bring it within the allotted space, 

 while to its right is practically the whole 

 of a bush ]:)lant, the leaves having been 

 removed from both specimens that the 

 character of the stems may be better 

 seen. The eye quickly catches certain 

 marked differences in detail, as, for 

 example, the comparatively long, slender 

 internodes in the \'ine type in striking 

 contrast with the short and thick ones 

 of the bush plant. The few remaining 

 young leaves do not indicate the large 

 difference in size in the mature foliage. 



STEM THICKENS SUDDENLY 



Attention is invited to the slender 

 base of each branch in the bush plant. 

 For one or more internodes the stem is 

 similar to that of the vine but as soon 

 as the region of bloom is reached, the 

 internodes remain short and take on a 

 remarkable thickening. The practical 

 utility of the long, slender, basal inter- 

 nodes is not far to seek, for by this 

 method of growth the extremely leafy 

 portion of each branch is carried farther 

 from the center of the jjlant and from 

 the shade produced by the foliage of the 

 main stem. 



O. F. Cook^ has suggested the term 

 Brachysm for this shortening of the 

 internodes as above mentioned, and is 

 of the opinion that it is not an exam])le 

 of the l)eginning of a new character, 

 although of much interest in the- study 

 of heredity and evolution. 



The records show that the average 

 weight of the ri])e fruits from the vine 

 l)lants was 692.2 grams and from the 



'Brachysm — A Ilcrcflitary Deformity of Cotton and ()ihcr Plants. O. F. Co<ik, Journal 

 Agricultural Research, Vol. III., No. 5. 1915. 



270 



