TRANSACTIONS OF THE SECTIONS, 87 
have found that the colour stripe is not visible in the petals while they are entirely 
covered by the calyx; but that when the calyx, ‘opening in a slit across the apex of 
the bud, presents to the light a portion of the petals folded on one another, this pore 
_ tion, and this only, acquires the deep red dye which makes the colour stripe, When, 
__asis often the case, one petal is so folded as to cover or nearly cover all the others, 
__ and the opening of the calyx passes over it alone, this petal receives the whole dye; 
it alone is striped, and the stripes converge toa point ; but when the outer petal does 
not so fully cover the others, and the opening crosses not the surface of that petal only, 
but also the edges and surfaces of one or more of the others, these edges and surfaces 
partake of the red stripe, which is really in its origin one continuous band on the bud. 
From these facts it may be concluded that the limited red dye of this rose is due 
to light acting during a very short period of time on whatever cells of the petals 
may happen to lie in the zone which is uncovered by the calyx and released from its 
pressure ; that there is no peculiar susceptibility for colour in these cells which di-. 
stinguishes them from the others, all being in fact susceptible of this colour, but only 
in a particular stage of growth, viz. that which precedes the full opening of the calyx 
into its five segments, 
In a few cases it has happened that one of these rose-buds opening in a very 
‘shady situation has received no red dye, but remained altogether white; and by ex- 
-perimentally covering a bud with a black hood, the development of red dye has been 
_ entirely prevented. A bud entirely covered with a glass case was very much re- 
_ tarded in flowering, and opened colourless. 
= I have found, by examining many other roses, single and double, that the same 
_ principle, of the colour depending on partial exposure of the petal to light at a par- 
ticular epoch of growth, is capable of extensive application to white roses whose 
_ outer petals are in any degree dyed red ; but it seldom happens that in rose petals the 
_ susceptibility for a red dye is so remarkably limited as in the example chosen; the 
_ dehiscence of the calyx determines indeed in many cases a band or bands of darker 
_ tint, but this generally spreads so far to the right and left beneath the leaves of the 
calyx, as not to catch the attention, 
Ido not venture at present to offer this explanation of the tints of these roses as a 
_ general view applicable to other flowers, in which, frequently, there is a specific de- 
termination of colour to specific parts of the floral envelopes ; but I think it probable 
_ that many striped and spotted flowers may yield to observation and experiment proof 
_ that the distribution of their hues is in some degree governed by the manner in which 
_ their buds are released from pressure and exposed to light, 
& On an apparently undescribed state of the Palmellee, with a few Observations 
on Gemmation in the Lower Tribes of Plants. By G. HK. Tuwatrzs. 
The Palmellee are usually described as consisting of separate cells, imbedded in a 
gelatine, each cell being supposed to represent a single plant. Mr. C. I. Broome, 
_ however, has discovered that in an early stage of Palmella botryoides of Greville, the 
_ plant consists of a number of branched filaments without septa, containing endo- 
chrome, and having their ultimate ramifications terminated by the ordinary cells of 
‘the Palmella; around each of these cells a quantity of gelatine is developed ; they 
Subsequently become detached from the filaments, and develope the mucous pro- 
ongations, which, as Mr. Hassall has observed, are probably characteristic of most, 
_ if not all the species of this tribe of plants. Mr. Broome’s observations have been 
_ confirmed by the author in the species above-mentioned, as well as in Coccochloris 
_ rufescens, Brébisson?, another species of the Palmeliee. Mr, Thwaites considered 
then assuming an independent vitality, should be viewed as a gemmation taking place, 
_ being rather a division of the individual plant than a reproduction of the species ; and 
therefore the subsequent fissiparous division of these separated cells would be a con- 
tinuation of the same process of gemmation. The author proceeded to show to what 
extent gemmation takes place in the lower tribes of plants, instancing the mosses, in 
' which it would appear to commence even in the subdivision of the contents of the 
" sporangium ; if the mass of sporules is to be considered, as seems probable, the repre- 
. Sentative of one embryo in the higher plant, the phytons produced from the con- 
B; 
