274 



BOTANICAL GAZETTE 



[OCTOBER 



striking in the hybrids, whereas those of the father, O. biennis, 

 have only a less influence on the general type. 



In table XI the figures of table IX are combined with the per- 

 centages derived from my Gruppenweise Artbildung, by taking the 

 means of the two crosses for each case given on pp. 251 and 261. 



TABLE XI 

 O. canay.0. biennis compared with 0. lata and 0. scintillans 



In this table we see that the characters of 0. cana, even as those 

 of O. scintillans and O. lata, are repeated in about one-half of the 

 progeny, but not in the other half. We may consider this as the 

 simplest case. In the other crosses the proportions of cana are 

 17, 25, 28, with a mean of 23 per cent in table IX, and 21, 40, 42, 

 mean 34 per cent in table X, and these figures may be assumed to 

 point to a splitting into nearly equal parts with a loss on the side 

 of the weaker form. Exactly the same behavior occurred among 

 the progeny of the self-fertilized individuals of 0. cana, as we have 

 seen previously. 



Let us now compare 0. cana with the two allied forms in those 

 crosses where the progeny splits into the twin hybrids 0. laeta and 

 0. velutina, as shown in table XII. 



The types of O. laeta and O. velutina have been compared in 

 each case with the twins derived from 0. Lamarckiana by the same 

 father." The comparison embraced the whole lifetime from the 

 germination in February until the production of the fruits in 

 September. No differences have been observed. 



From table XII we see that the splitting percentages"" are 

 practically the same, whether the pollen is taken from 0. biennis 

 Chicago, 0. Cockerelli, or O. Hookeri. For this reason I have given 



" DeVetes, Hugo, On twin hybrids. Bot. Gaz. 44:401-407. 1907. 



