SOL'TIIWORTH : AUFAI.FA HYBRIDIZATION 



451 



in certain districts is due to the lack of 

 fertilization of flowers owing to a scar- 

 city of suitable insects to carry out the 

 necessary operation of liberating 

 stamens and pistil from the keel. 



BLACK MEDICK SELF-FERTILIZED. 



As previously stated, the black 

 medick is frequently regarded as a 

 weed, and most farmers and botanists 

 are well acquainted with its marked 

 capacity to produce seed no matter 

 whether the season is favorable or other- 

 wise. This capacity to seed freely under 

 varied climatic conditions is doubtless 

 owing to its being apparently normally 

 self-fertilized and not requiring the aid 

 of bees or other external agency to 

 ensure pollination. 



This property which black medick 

 possesses of producing seed from self- 

 fertilized flowers was investigated by 

 Darwin and in his ' ' List of plants fertile 

 without insect aid," dealing with Medi- 

 cago lupulina, he gives the results of his 

 experiments as follows : 



"On account of the danger of losing 

 the seeds, I was forced to gather the 

 seeds before they were quite ripe; 150 

 flower heads on plants visited by bees 

 yielded pods weighing 101 grains whilst 

 150 heads on protected plants yielded 

 pods weighing 77 grains. The in- 

 equality would probably have been 

 greater if the mature seeds could have 

 been all safely collected and compared."^ 



In recording the resiilts of his own 

 observations made in 1894-5 Burkhill 

 describes^ the form and mechanism of 

 the flowers of black medick as being 

 similar to that of the common lucerne, 

 but in the flowers of the former plant the 

 stamens and pistil are much more easily 

 liberated from the keel. 



In regard to seed-production, Burk- 

 hill found that where flowers of black 

 medick were left exposed to the visits 

 of insects 95% produced seed, when 

 enclosed in a net 75% of the flowers set 

 seed. 



In the course of our tests (not know- 

 ing of any previous investigations having 



1 Darwin, Charles. The Effects of Cross Fertilization in the Vegetable Kingdom, p. 368. New 

 York, 1877. 



- Burkhill, I. H. On the Fertilization of Some Species of Medicago, L., in England. Proc. 

 Camb. Phil. Soc, Vol. 8, p. 142, 1892-1895. 



been made on this subject) we enclosed 

 the flowers of black medick in a muslin 

 cage similar to that used for alfalfa 

 flowers. 



The object of the test was simply to 

 see whether or not the black medick 

 flowers would produce seed when bees 

 and other insects were excluded. It 

 was found that the protected flowers 

 set seed apparently almost as well as 

 those which were fully exposed. No 

 attempt was made to make an exact 

 count of seeds or pods obtained by the 

 two methods as so many of the pods 

 were lost on ripening it was not possible 

 to make a comparison which would 

 have been strictly accurate. 



The above tests all indicate that in 

 black medick we have a plant in which 

 the free seeding propensities are de- 

 veloped to a high degree of perfection. 

 This property, I need scarcely say, is of 

 immense value as a rapid and easy 

 means of reproduction and is a charac- 

 teristic which if it can be successfully 

 combined with our present strains of 

 alfalfa will so enormously enhance their 

 usefulness that the increase in the value 

 of the crop as a whole can not be well 

 estimated. 



THE BREEDER'S PROBLEM. 



Having arrived at this point our 

 problem will now be clearly seen as 

 being : 



(1). An attempt on the one hand to 

 combine the high crop-producing prop- 

 erties of alfalfa with the free seeding 

 propensities of black medick. 



(2). To try to effect a suitable com- 

 bination between the hardiness of al- 

 falfa and the fine growth of foliage and 

 valuable grazing properties of black 

 medick with a view to the development 

 of a plant suitable for pasture purposes. 



The first alfalfa mother plants to be 

 used were selected from individuals 

 from strains originally obtained froin 

 the United States Department of Agri- 

 culture, Washington. 



The work was commenced in June, 

 1911, and carried on throughout the 



