66 
GENETICS: D. F. JONES 
Proc. N. a. S. 
many characteristic furnace lines which the spark emits very faintly. 
An outstanding feature of these lines for the iron spectrum is a prevail- 
ing large separation and simple triplet structure. Lines of this class are 
often of special interest in the study of sun-spot spectra. 
The furnace offers unique facilities for the production of the inverse 
Zeeman effect when a plug is placed in the tube. The absorption spectra 
resulting from this arrangement were discussed in the preceding com- 
munication. An extended study was made of the magnetic components 
given in absorption by this method. No difference was observed as to 
character or magnitude of separation as compared with the effects for the 
emission spectrum. A means of direct comparison with the magnetic 
effects for absorption lines in the solar spectrum is thus afforded, which may 
be expected to be very useful in tests as to polarization and other features 
at various angles to the lines of force. 
SELECTIVE FERTILIZATION IN POLLEN MIXTURES 
By D. F. Jones 
Connecticut Agricultural Experiment Station, New Haven 
Communicated by T. B. Osborne, Read before the Academy, November 10, 1919 
The fact of self -sterility or self-impotency is well established in many 
species of plants and in at least one family of animals. It is also believed 
that even in the normal condition of self -fertility the germ cells from 
different, unrelated individuals in some cases are more efficient in ac- 
complishing fertilization than the germ cells from the same or similar 
individuals. Statements to this effect are made in text books on biology. 
A simple method of accurately testing this assumption is available in 
the use of pollen mixtures which carry such inherited characters that the 
different kinds of seeds resulting from the pollinations can be distinguished. 
By taking pollen from two distinct types of maize, designated A and B, 
in approximately equal quantities, thoroughly mixing, and applying the 
mixture to the plants which furnish the pollen, it is possible to obtain and 
to separate the two kinds of seeds on each plant. On the A plants the 
seeds are A X A self -fertilized and A X B cross-fertilized. Similarly, 
on the B plants the seeds resulting from the mixture are B X A cross- 
fertilized, and B X B self-fertilized. The numbers of individuals in 
each class form a proportion such that the A X A seeds are to the A X B 
seeds (produced on A plants) as the B X A seeds are to the B X B seeds 
(produced on B plants). The end terms of this proportion represent self-, 
fertilized, while the middle terms represent cross-fertilized seeds. If 
fertilization takes place at random the numbers form a perfect propor- 
tion, irrespective of the relative amounts of functional pollen present in 
the mixture and independent of the total number of seeds obtained from 
