Varietäten etc. — Physiologie. 635 



view to the development of a plant suitable for pasture properties. 

 The writer has made preliminary experiments to obtain infor- 

 mation on the following points: 



1. When alfalfa is in flower what etfect, if any, has the exclu- 

 sion of bees and other insects on seed production? 



2. If alfalfa flowers be self-pollinated by hand and insects excluded 

 are they sterile er fertile? 



3. If it is the case that insects are essential to ensure fertili- 

 zation, what species appear to be raost successful in performing 

 the Operation? 



The results ofthe writers work in respects to these questions are: 



Alfalfa apparently does not seed freely in absence of suitable 

 insects to insure fertilization of the flowers. Wild bees of the Mega- 

 chile species seem to be most effective in insuring fertilization. 

 Alfalfa flowers are not self-sterile and may be artificially self-ferti- 

 lized with good results. Black medick is capable of self-fertilization 

 and produces seed freely even when insects are prevented gaining 

 access to the flowers. 



Besides these researches, the writer made some hybridizing 

 experiments, that led him to the following conclusions: 



In the practice of hybridization of alfalfa better results are 

 obtained by working on mature flowers than by operating on flower 

 buds. The cross between alfalfa and black medick is efifected only 

 with considerable difificulty and prolonged effort is essential to War- 

 rant success. 



In the F^-Generation hybrids the plants were variable and usu- 

 ally greatly different from either of the parental forms. 



A study of the progeny of F.,-Generation revealed a tendency 

 to Mendelian segregation both in height of plant and habit of 

 growch, but further study is necessary to confirm these points. 



The difificulty often experienced of inducing germination in hard 

 alfalfa seeds may be successfully overcome by treating them with 

 strong commercial sulfuric acid. M. J. Sirks (Haarlem). 



Brown, B. S., Influence of stock on cion. (Journ. of Hered ity. 

 VI. p. 152—157. 1915.) 



The paper contains an interesting account of some unions of 

 almond and peach and of almond and plum. The firstnamed grafting 

 was made 42 years ago on the trees of a peach orchard, that where 

 used as Stocks for almondcions. The trees were generally spoken as 

 sodnd as they were at the age of five; many of them were 50 feet 

 high and ranged from two to three feet in diameter. The grafts of 

 almond on plum were less successful; the 42-years old cions had 

 well grown, but the plum Stocks had lagged behind; the result was 

 that they were unable to furnish as great a supply of sap as the 

 more vigorous top demanded, so most of the trees of this sort had 

 died or were dying. 



From these almond grafts, it will be evident that grafting may 

 increase the size not only of one parent, but of both; and in this 

 case, it seems to have resulted in increased longevity, as well. 



Some other influences of stock over cion are mentioned in this 

 paper: the early bearing tendency of dwarfed trees, the delay in 

 the blooming period of certain fruits when united with slow growing 

 Stocks; color and flavor of fruits, their sugar and acid content etc. 



