DR. BOSWELL-SYME ON FERTILISATION OF GRASSES. 7 
aphides from the Lime-tree he examined. Moreover, it was only- 
one tree which was attacked ; had aphides been the cause of the 
honey-dew, it is hardly likely that other trees at a little distance 
would have been, as was the case, perfectly healthy. The conclu- 
sion appears to be that while in some cases honey-dew is due to the 
presence of aphides, in others it is an independent result of a 
diseased condition of the affected plant. W. T. D. 
II. On the Fertilisation of Grasses. By J. Boswell-Syme, LL.D., 
F.L.S. 
[Read April 17, 1872.] 
Throtjgh the kindness of Professor Thiselton Dyer I have had an 
opportunity of reading Dr. Spruce's paper on the Fecundation of 
Grasses" (Journ. E. Hort. Soc, n.s. iii., pp. 4 — 9.) As I do not 
find in it any record of observations bearing on the fertilisation of 
Cereals, there is no necessity for me^to discuss the opinion expressed 
by Dr. Spruce on the subject of the cross-fertilisation of Wheat. 
There are, however, two points in which his experience of South 
American Grasses is at variance with what occurs among our British 
species — first, the change of colour of the anthers from some 
shade of purple to yellow and back again to purple ; and second, 
that the absence of odoriferous flowers from the Grasses seems to 
show that insect aid is not needed for effecting their fecundation, 
but does not render its accidental concurrence a whit less unlikely," 
which seems to imply that insects are not attracted by inodorous 
flowers, and as a special application of this, that Grasses when in 
flower are not regularly visited by insects. First, in British 
Grasses and those ordinarily cultivated there are a few which have 
their anthers always purple {Corynephorus canescens and Molinia 
ccerulea for example) ; there are many in which they are pale yellow 
or yellowish-white {e.g., Spartina, Nardus, Lepturus, and all the 
commonly- cultivated Cereals) ; there are many also in which some 
individuals have purple, and others of the same species have 
yellowish- white anthers {e.g., Alopecurus pratensis, A. geniculatuSy 
Phleum pratense, Anthoxanthum, Dactylis). But in this case we 
never find the two colours of anthers on one root. My attention 
was directed to this by the Rev. W. W. Newbould, who wished 
me to see if there were not other differences between the white and 
