152 BOTANICAL GAZETTE. ' [June r 



placed in a deep glass vessel filled with water, and set where there would 

 be plenty of light and warmth, but to the exclusion of all insects natur- 

 ally visiting such blossoms. After a few hours a jar was placed upon a 

 table and the flowers inspected for sensitiveness. A large bull's-eye con- 

 denser was adjusted upon its tall stand so that a head of flowers came 

 into full view. Then, with the eye intent upon the particular blossom,, 

 the various floral parts were touched with the point of a needle. 



By this method the first reward was Echinacea angustifolia. In this 

 the whole flower, when touched upon one side, will move in a direction 

 opposite to that of the irritant; that is, if pushed by the needle upon the 

 south side, the top of the flower will move south, and through a distance 

 averaging its own diameter. At the same time there is a contraction or 

 drawing down of the ring of anthers equal to one-half of the diameter. 

 This motion takes place quickly and leaves the lemon-colored pollen ex- 

 posed upon the tip of the style, which may already extend somewhat 

 above the anther-ring. Unusually good results are obtained with flowers 

 which as yet show no portion of the style. In such the ring will contract 

 and show the first pollen in profusion upon the extremity of the style. 

 After an hour or so the flower again becomes irritable, and the anthers 

 will retreat farther, leaving a fresh supply of pollen exposed upon a lower 

 section of the style. The contraction is such that in many instances there 



is a revolving motion to the flower, as has often been seen in the thistle. 

 In the Echinacea there are none of the peculiar hairs exhibited by the 

 thistle filament, the surface being smooth throughout. 



The observations which have been stated for the Echinacea hold true 

 in a general way for Heliopsis tevis, although there are minor differences 



not worthy our present attention. 



A third species to be added to the list of sensitive flowers is Lep 

 chys pinnate, and a fourth is Rudbeckia hirta. 



With 



sometimes be obtained in the field, but as insects are usually abundant 

 the laboratory method is much more satisfactory. The writer would be 

 pleased to learn what other Comjpositse have been found in this country 

 illustrating sensitiveness of the stamens.— Byron D. Halsted, Rutgm 

 College, New Brunswick N. J. [Mr. Thomas Meehan has investigated this 

 matter at considerable length, but ascribes the movements to elasticity 

 and not sensitiveness. See abstract of his paper in Proc. A. A. A. B, 

 Phila. meeting, papers in Proc. Phila. Acad., and various abstracts and 

 notes in this journal.— Eds.] 



Peronospora upon cucumbers.-On May 8th, while taking a run 

 through the greenhouses and grounds of Mr. J. T. Hill here in New Bruns- 

 wick, my attention was attracted by the numerous light patches upon the 

 leaves of some cucumber vines which were growing in a hot-bed and al- 

 ready bearing fruit suitable for the table. Upon examining these spots 

 they were found to be due to a growth of some species of the genus Per- 



