102 
Davey^ on Bryonia Dioica. 
consist of an elastic material_, Ml of granules^ but otherwise 
destitute of structure ; after a short period^ this granular 
mass presents a spongy appearance^ numerous irregular cavi- 
ties being developed in it. Some of the larger cavities 
exceed the smaller ones in the proportion of 3 to 1. After 
a variable period^ the cavities become better defined^ and the 
substance intervening between them appears thinner. The 
larger cells are then subdivided by septa^ apparently of the 
same plastic material ; these septa are formed at one side of 
the cavity^ and stretch gradually across it, and when they 
have reached the opposite side^ coalesce with it_, and thus 
divide the cavity into two. All this has been made out by 
Mr. Wenham_, from the examination of the parts in succes- 
sive stages ; and I have actually seen it occur in the bryony. 
As soon as the embryo leaf of the Bryony has become so 
far developed that its cells have assumed a somewhat regular 
form, and its central parts have acquired a greenish colour, 
small, transparent, rounded projections (embryo hairs) make 
their appearance at its margin; these are faintly granular, 
rapidly increase in length, and soon develop a cavity or 
cavities in their interior ; after their cavities have increased 
in size, and their walls have become more marked, they com= 
monly assume a kidney-like form, and a septum of proto- 
plasm passes across to the opposite side and effects division 
of the cell ; the hair is thus divided into cavities of tolerable 
regularity. After these cells have become more shaped, the 
growth of the hair is continued in the direction of its length 
by globular masses of protoplasm which form at its extre- 
mity ; these, in the case of hairs upon the leaves and stalks, 
generally elongate, and sometimes farther subdivide, the result 
being a pointed hair of six or seven joints. In the case of the 
flowers and flower-stalks, the hairs do not attain the same 
form, but mass after mass of protoplasm is added to the 
extremity ; these retain more or less of their globular shape^ 
and form empty spaces within them of the most irregular 
form and number; some of the terminal masses havs no 
cavities, but, when the flower is mature, shrivel up without 
further development. I therefore believe, that as the flowers 
attain their growth, their hairs become abortive, and that the 
latter are not intended to reach the same dimensions and 
form as on the leaves and main stems. The utmost irregu- 
larity prevails as to the number of joints, cavities, &c., in 
these hairs from flowering parts ; some are even bifid : there 
is, moreover, far greater difiiculty in actually watching their 
changes, as their growth is comparatively slow in their latter 
stages. 
