138 MISSOURI BOTANICAL GARDEN BULLETIN 
discovered since 1900. In general, however, the law applies 
widely to such characters as the color and size of flowers 
as well as the coats of animals. Many vegetables and bloom- 
ing plants have been hybridized from this point of view 
and the predictions of particular crosses resulting have been 
proved to be correct. ; 
It has likewise been noted in Mendelian inheritance, show- 
ing the ratio of three to one, that it is impossible to dis- 
tinguish between true dominants and dominant ad babe 
their behavior in subsequent generations being the only test. 
On the other hand, the recessives with respect to any one 
character mk Spies in the second generation will subse- 
quently breed true for this character. Consequently, reces- 
sives give the practical breeder an opportunity of determin- 
ing the value of a new form much sooner than would other- 
wise be the case. 
Among the plants whose constitution has been investi- 
gated may be mentioned the primrose (Primula), sweet pea 
(Lathyrus odoratus), stock (Matthiola), four o’clock (Mir- 
abilis), violet (Viola), shepherd’s purse (Capsella Bursa- 
pastoris), tobacco (Nicotiana), foxglove (Digitalis), snap- 
dragon (Antirrhinum), as well as peas, beans, and various 
other vegetables. : 
Mendel believed that in order to study heredity intelli- 
gently it was necessary to contrast individuals in such a wa 
that they might be considered as constituting a pair, eac 
factor to be ses with a different one; for example, char- 
acters for yellow and green-seeded peas formed a pair. 
somewhat different conception is held at the present time, 
and it is now known that in some cases the codperation or 
presence of more than two factors which are independently 
inherited is necessary for the production of a particular 
character. It should be explained here that by a “factor”. 
is meant a difference in the germ which leads to the develop- 
ment of a particular character, and consequently the absence 
of any character means that the factor associated with it 
fails to develop. The fundamental nature of a factor is, 
however, only pore understood. In the case of the flowers 
referred to, at least one of the factors is always a chromogen, 
or color-producing substance, while others may be various 
enzymes or ferments which h i 
solr prodeed ch have an effect on the particular 
BIRDS IN THE MISSOURI BOTANICAL GARDEN 
The following observati 
Daniels and Mr. R. F. O'Neal. 8° °Y Mr. Edward 8. 
