Plaxt-15reeding for Farmers. 139 



seedlessness throughout the entire individual. It would not be the correct 

 policy for a breeder to select simply a single fruit which might 

 accidentally be nearly seedless. He should examine a large number of 

 fruits of different individual plants, and find a plant on which he can dis- 

 cover a general tendency toward seedlessness, showing in all of the fruits 

 produced. By selecting seed from such individuals he may be able to 

 find in time one such individual that would transmit to its progeny this 

 tendency to produce few seeds. 



While this is certainly generally true, there are some instances in which 

 further divisions of the individual are important. As an illustration may 

 be mentioned the case of color in corn kernels. Where one is dealing with 

 hybrids of corn of different color it is well known that the kernels on the 

 same ear may vary in color, and if the investigator is attempting to produce 

 a certain color he should select to plant only those kernels that have the 

 color which it is desired to produce in the new strain. 



In head selection of wheat and oats made in the field as described in 

 another part of this bulletin, one is in a sense basing the selection of an 

 individual on the examination of one part. However, this head selection 

 should be accompanied by an examination of the plant to some extent 

 and even if this is not done the planting of each head in a test row by itself 

 to determine comparative yield, gives a measure of the productivity of the 

 original plant from which the head was taken and this after all is the im- 

 portant point. 



Again in clonal-breeding^, the unit used is any part or portion of the 

 plant that shows a desired variation. In potatoes where the hill method 

 of selection is used the unit would be the tuber producing the hill, and the 

 yield of the hill would be the measure of the productivity of the bud that 

 produced the tuber. In breeding carnations, violets, pineapples, and 

 the like, by the selection of cuttings or slips, the plant grown from the 

 slip or cutting becomes the unit representing the productivity of the bud 

 which produced the slip. 



Test of transmitting power. 



A factor of primary importance in all pedigree or grade-breeding is the 

 testing of what is termed the transmitting or centgener power. It is neces- 

 sary for us to know that a certain plant, which for instance, gives a 

 heavy yield, has the faculty of transmitting this tendency of producing 

 heavy yield to its progeny. It is frequently found that two select 

 plants which are equally good so far as their yield is concerned will give 

 progeny which, as a whole, differ greatly in this respect. In the progeny 

 of one almost every plant may have inherited the quality, while in the 



1 Clonal-breeding,— breeding by the selection of vegetative parts, buds, scions, 

 tubers, bulbs, slips, etc. 



