58 BULLETIN 428, U. S. DEPARTMENT OF AGRICULTURE. 
With the Grimm variety as an example of what may be accom- 
plished through the aid of the southern forms of Medicago falcata, 
even better results may be expected from the crossing of good north- 
ern forms with Medicago sativa. Some very promising hybrids 
have already been made between the Peruvian and Arabian alfalfas 
and a fairly erect type of Medicago falcata similar to the form illus- 
trated in figure 17. These hybrids combine valuable characters, in- 
cluding to a rather remarkable degree the quick recovery and growth 
of the Peruvian and Arabian varieties and the low crown and abun- 
dant tillering of Medicago falcata. Furthermore, they have proved 
to be reasonably hardy at Highmore. The advantages of such hy- 
brids can readily be appreciated. 
The proliferating root character, as found in certain forms of 
Medicago falcata, has only recently been observed in this country. © 
By the use of this character, high-yielding strains may be originated - 
that will be especially resistant to severe climatic conditions and 
actually aggressive on soils of fairly loose texture. 
The above are only a few of the possibilities that are offered to the 
plant breeder by this diverse species, and those who fail to see beyond 
its agronomic defects as it exists in its natural state are missing an. 
opportunity in the field of plant breeding. 
ARTIFICIAL AND NATURAL HYBRIDIZATION. 
There are two ways of utilizing Medicago falcata in the develop- 
ment of hybrid strains of alfalfa; namely, in the making of natural 
and of artificial hybrids. The latter is the more definite and promis- 
ing method, but the former unquestionably offers possibilities. In the 
making of artificial hybrids both parents may be carefully chosen 
and rigid selection made in the progeny. While the expense incident 
to this method is considerable, satisfactory results can be secured 
from it in a much shorter time than from the latter method. Polli- 
nation by artificial means is easily accomplished, either by what is 
termed the depollination method or by tripping the flower of the 
plant selected for the female parent on a knife blade or similar instru- 
ment upon which pollen from another plant has been collected. On 
account of its comparative simplicity the latter method is generally 
preferred. It appears to be true that the pollen of Medicago falcata 
is prepotent over that of I/edicago sativa on the stigmas of the latter, - 
and vice versa. At any rate, there is very little difficulty in effecting 
reciprocal crosses between the two species. Methods of pollination 
have been fully discussed in bulletins of the Department of Agricul- 
ture (46) and other institutions. 
The fact that the hybridization which has produced the variegated 
commercial strains of alfalfa has been the result of natural agencies . 
leads to the belief that with careful work still better results may 
