June. 191 7| Xenia Following Fertilization 279 



The Nature of Some Effects Following 

 Fertilization. 



Some of the examples that have recently been brought to 

 the writer's attention are: 1. The common folklore of farmers 

 that watermelons pollinated by pumpkin pollen have a lower 

 sugar content. This matter has also been made the subject 

 of investigation recently. 2. A report by Daniel (12) of a 

 walnut containing a hazel nut kernel. 3. A change in the 

 sugar content of dates due to pollination. 4. A change in 

 the color of the shell of fowl's eggs due to the influence of the 

 male bird. 



While some of these influences are not yet fully recognized, 

 the author will not attempt here to confirm or deny the existence 

 or non-existence of any of them. But since they are being 

 pushed forward for discussion, those who are interested in 

 them should insist that they be discussed in proper terms 

 and not confuse them with another effect the nature of which 

 is just beginning to be understood, and the term used to describe 

 this effect just acquiring a distinct, comprehendable meaning. 



In the case of the cucurbits, the date and a number of 

 similar examples there is an effect occurring in the fleshy 

 pericarp at a greater or less distance from the region of fertiliza- 

 tion. Focke's observations on grapes belong under this head. 

 Now that we know the facts about triple fusion it is obvious 

 that this effect cannot be xenia. Although it follows fertilization 

 it is not so closely connected with it that it is possible for 

 determiners brought in by the pollen to be expressing them- 

 selves. The pollen cannot produce an effect in the pericarp for 

 the determiners expressing themselves in the pericarp belong 

 to the preceding sporophyte generation. Exactly what causes 

 the change is not known, but one might postulate a specific 

 chemical reaction following a specific pollination. 



This is a very different thing from xenia. In xenia there 

 is merely the expected expression of determiners capable of 

 expressing themselves in the endosperm. There is nothing 

 strange about it, except that they are appearing in a new 

 place, that is in a race or variety in which they had not previously 

 made an appearance. If any xenia occurred in dates or water- 

 melons it would have to be inside the seeds, not in the fleshy 

 pericarp. 



