272 MR. A. W. BENNETT ON CLEISTOGAMIC FLOWERS. 



entry of the tubes into the ovules has been observed ; nor, in the 

 very large number of specimens examined by me, have I been 

 completely successful on this point. It appears to me that, as 

 D. Miiller and Von Mohl observe, the process must take place 

 with great rapidity, and be consequently very difficult of detection. 

 It is, however, very easy to get good sections of the opening of 

 this passage into the ovary, and I have never been able to 

 detect the least trace of pollen-tubes entering the ovary by this 

 means. Moreover, where they can be seen passing from the 

 anther into the stigma, they enter, as it seems to me, not the 

 funnel-shaped cavity but its anterior wall (figs. 4, 5, b). The struc- 

 ture of the ovules in Viola seems also to negative the probability 

 of the pollen-tubes entering the ovary in this way. These exhibit 

 in this genus, as is well known, an extreme instance of the ana- 

 tropous structure, which is as marked in the cleistogamic as in the 

 perfect flowers, the large micropyle being brought into very near 

 contact with the wall of the ovary. This -j^ g # 



structure would appear to be a decided dis- 

 advantage if the pollen-tubes reached the 

 ovary through the open passage at its apex ; 

 and I am inclined to think that their mode of 

 access must be the same as that observed by 

 Dr. P. M. Duncan in the case of Primula, 

 through the tissue of the wall of the ovary 

 itself, whence they diverge in close proximity 

 to the placenta, and consequently to the mi- Viola sylvatica. 

 cropyle of the ovule. I express this opinion, General view of cleis- 

 however, with considerable diffidence ; and °g amic 

 more exact observations on this point are wanted, as well as on 

 the purpose of the passage through the style, which Mr. Darwin 

 states does not exist in the perfect flowers of V. canina. 



V. sylvatica, Fries. — The cleistogamic flowers appear in great 

 numbers throughout the autumn. They are about one eighth of 

 an inch in length. The calyx (fig. 9) consists of five sepals, which 

 are only slightly imbricate and unequal in size ; two adjacent 

 (inferior) sepals are prolonged at the base into an auricle, and 

 also somewhat overlap the rest at the apex ; the two lateral ones 

 are the smallest, and the superior sepal is of intermediate size. 

 The corolla is, as far as I could detect, completely abortive. The 

 ovary is nearly spherical ; the style is very short and curved, so as 

 to form a semicircle, the stisrmatic surface facing downwards, as 



