178 ‘MR. T. Н. CORRY ON ASCLEPIAS CORNUTI. 
corpusculum or tuberculum.” Of these designations, the simple name * corpusculum ” 
is infinitely the more preferable, since the former conveys a totally erroneous idea as to 
the real nature of the body ; forit is not a gland which secretes at all, but a true excretion. 
From the mode of formation of the corpusculum, then, it may be gathered that 
it encloses a hollow or cavity, which is narrower above, where, owing to the overlapping 
of the rounded eave of the style-table, the sides of the furrow which formed it meet the 
floor; that it is further closed posteriorly, but open anteriorly, for in the latter part the 
masses of gum lying at the mouth of the furrow project, i. e. are bent forwards and 
inwards over the longitudinal hollow, while at the same time they oppose each other 
and are approximated closely together. They converge more above than below, owing to 
the shape of the furrow which excreted them, so that the deep longitudinal fissure which 
is left between them (for they never meet) is wedgeshaped. In consequence of the 
existence of this fissure, which is widest inferiorly, narrowing above, the whole corpus- 
culum appears, when viewed iz situ from the front, to be imperfectly cleft or divided in 
a symmetrical manner into two halves or valves. The slightly curved projecting margins 
or edges, which were first formed, and hence have dried more than the rest and become 
harder, do not end superiorly by uniting, but are distinct for their whole length; as, 
indeed, is a matter of necessity owing to their mode of formation. Finally, the lumen of 
the corpusculum is completely open inferiorly, where the wider deeper excreting portion 
of the original furrow becomes continuous with the narrower non-excreting part (vide 
figs. 14, 15, 19). By degrees the hardened mass of gum becomes more solid, and is 
easily separable as a single mass from the furrow; it exhibits no longer any indication 
of a suture, or of having originally consisted of two distinet parts, and is loosened from the 
cells which excreted it. It may then be found no longer, as heretofore, closely lining 
the furrow, but lying on the contrary somewhat loosely at its mouth, while the epidermis, 
which excreted it, is quite uninjured and continues uniformly to line the furrow just as 
before. The whole corpusculum has now dried so completely that only a striated 
appearance in transverse section remains to indicate its original origin. It forms a thin 
hard firm body with a shining surface, of a cartilaginous or horny texture when cut, 
and of a dark black or reddish brown colour. Its uniform nature is seen by treating a 
thin transverse section with a strong solution of caustic potash. The results of my 
researches as to the origin and development of the corpusculum are directly opposed to 
the view of Schleiden (doc. cit. p. 382), who, from some observations on Gomphocarpus, 
R. Br., and Hoya, R. Br., thought that probably the outermost borders of the anther- 
wings are formed rudimentarily very early at the five upper ends of the stigmatic furrows, 
_ во that each body (corpusculum) originates from the cohesion of two fragments of two 
different anthers, though he admits that the point is one of the most difficult to investigate 
that he knew of. Тһе younger Reichenbach also remarks, concerning this view, that in 
Dictyanthus, Decaisne, the lateral processes of the anthers do not touch the angles of the 
style-table, so that in this genus at least the corpuscula could not be so formed. 
My results, however, completely confirm and more fully carry out the imperfect and 
fragmentary observations of Schacht and the younger Reichenbach as to the mode of 
origin and nature of these bodies. Robert Brown, who was the first observer to investigate 
