382 Tricofyloiis Races. 



them out and allowed them to flower in isolation. 

 Higher ])roportions are thus obtained : for instance in 

 cultivated species in Cclosia crisfafa 2^c , in Clirysaii- 

 thcniuin Mycoiiis 1-2^6, in Oenothera longifolia V/( , O. 

 mollissiina V/o , O. uudulaia, 1%, Xylopleunini tetra- 

 pteriun 2%, Podolcpis gracilis 2^/c, Tctragonia expansa 

 2%, Veronica longifolia 4%; and amongst wild species 

 in Chenopodiujn album 1%, Thrincia hirfa 1%, and so 

 forth, the two latter having been grow for three genera- 

 tions. Further instances will be afforded by the be- 

 irinnines of mv cultures to be mentioned below. 



If we compare the proportions just given, excluding 

 those species which are so rich in tricotyls that they 

 probablv contain an intermediate race, we find from 

 0-2 tricotyls in about every 10,000 seeds, from mate- 

 rial which lias 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 

 orisfinal mixtures, therefore, must have contained the 

 seed of many individuals witliout 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 

 eenerations, or whether it maintains itself without chang- 

 ing. As I have already stated, the conclusion derived 

 from mv 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 ])lace even if the selection 

 is continued for many years. Obviously this depends 

 on the (|ue>^tion whether an intermediate race is present 

 in tlie given sample of seed, or not. If it is there, it 



