382 Tricotylons Races. 
them out and allowed them to flower in isolation. 
Higher proportions are thus obtained : for instance in 
cultivated species in Celosia cristata 2%, in Chrysan- 
themum Myconis 1-2%, in Oenothcra lone/if olia \%, 0. 
mollissima \%, 0. undnlata, 1%, Xylopleurum tetra- 
ptcrum 2%, Podolepis gracilis 2%, Tetragonia c.vpansa 
2%, Veronica longi folia 4% ; and amongst wild species 
in Chenopodmm album \%, Thrmcia hirta 1%, and so 
forth, the two latter having been grow for three genera- 
tions. Further instances will be afforded by the be- 
ginnings of my cultures to be mentioned below. 
If we compare the proportions just given, excluding 
those species which are so rich in tricotyls that they 
probably contain an intermediate race, we find from 
0-2 tricotyls in about every 10,000 seeds, from mate- 
rial which has been bought or obtained by exchange or 
collected in the field, whilst the harvest obtained after 
the isolation of the tricotyls, contains from 1-2%. The 
original mixtures, therefore, must have contained the 
seed of many individuals without tricotylous offspring. 
Besides the hereditary capacity of bought seed and 
of the tricotyls raised from it after artificial fertilization, 
we have to consider the question whether this capacity 
can be increased by a selection extending over several 
generations, or whether it maintains itself without chang- 
ing. As I have already stated, the conclusion derived 
from my experiments is that the answer may fall into 
one of two categories. In some species selection may 
soon lead to a proportion of 50% tricotyls and more; 
in others, this does not take place even if the selection 
is continued for many years. Obviously this depends 
on the question whether an intermediate race is present 
in the given sample of seed, or not. If it is there, it 
