Summary. 573 



That is to say a definite though shght decrease in the 

 mean number as the resuh of fairly rigid selection. 



§ 9. SUMMARY. 



In conclusion, I will give the results described in the 

 last three sections in a short summary. 



The general result is that they are in complete har- 

 mony with those obtained with Oenothera Lamarckiana 

 and O. rubrinervis (§§ 4-5) and can therefore be re- 

 garded as a confirmation of these. 



They show that when nutrition and selection are 

 brought into conflict, in some cases one of them triumphs, 

 and in others the other. In Anethum it was nutrition, in 

 Coriandrum and Madia selection, in Chrysantheumm, 

 Coreopsis and Bidens it was a drawn battle. The differ- 

 ences between the results of the individual experiments 

 has evidently more to do with the relative power of these 

 two factors than with any putative differences between 

 the species investigated. For obviously the same amount 

 of manure per square meter means a very different 

 amoujit of nutriment for different plants; and, on the 

 contrary, selection, however stringent it may be, is effec- 

 tive in analogously different degrees. 



We conclude, therefore, that selection and nutrition 

 influence the plant in the same direction and that it de- 

 pends on circumstances whether the one or the other of 

 the two preponderates. 



Perhaps the simplest and clearest way of proving 

 this generalization is to exhibit the means of the num- 

 bers of rays and ray-florets of the primary inflorescences 

 of all the species investigated. 



