1846.] 



Linnean Society. 



297 



The second Table is copied from the Journal kept in succession 

 by Dr. Forster's late father, T. F. Forster, Esq., F.L.S., and himself; 

 and records the period of arrival of the Swallow {Hirundo rustica, L.) 

 for nearly half a century. Dr. Forster hopes on a future occasion to 

 supply similar tables of the Martin, Swift, and other birds of passage. 



Read also a note " On the Structure of Viola, in connection with 

 its Impregnation." By T. S. Ralph, Esq., A.L.S. &c. 



Mr. Ralph regards the following circumstances as more or less 

 essential to the impregnation of the ovules of Viola : 1st, the pen- 

 dent position of the flower, which brings the stigma into a position 

 below the anthers ; 2ndly, the spurred petal, which by the secretion 

 of honey attracts insects, whose efforts to obtain a supply of nutri- 

 ment disturbs the whole band of coherent anthers through the move- 

 ments impressed on the two spurs of anthers which descend into the 

 nectary, and thus cause a free discharge of pollen ; 3rdly, the rostrate 

 termination of the stigma in some species, in which the pollen is 

 shed very freely and appears to have a ready access to the interior 

 of the stigma ; 4thly, the remarkable bend in the style in those spe- 

 cies which have a globose stigma, in which species Mr. Ralph has 

 also found a set of singular hairs seated on the claw of the fifth or 

 spurred petal, on which the pollen collects very abundantly, and 

 thence probably finds its way into the interior of the stigma ; the 

 stigmatic head being readily capable of being pushed into the groove 

 of the claw of the petal amid these hairs, a process which Mr. Ralph 

 thinks is performed by the assistance of insects. In some species 

 there are also a set of hairs placed at the throat of the corolla on the 

 two middle petals, the use of which Mr. Ralph thinks to be to shut 

 out the ingress of the proboscis of the insect in that direction. 



