SECRETION IN THE HYPERICACE® 455 
Wien by Dr. F. R. von Hóhnel upon the structure of glands, in 
which he goes more into the details of the manner in which they 
originate. He agrees with Frank as to the schizogenous origin 
of the cavities. Of the species of Hypericum he worked chiefly 
at H. perforatum and H. montanum, in both of which he de- 
scribes two kinds of glands, the pellucid and the dark-colonred. 
He says these differ further in the contents of the cells of the 
latter being solid. Both are of similar construction and mode of 
origin, arising from young mesophyll-cells abutting on one or 
other epidermis. Those which, in the thicker-leaved species, lie 
deeper in the tissue, arise from cells farther from the epidermis. 
He goes on to describe the mother cell of the pellucid gland 
as dividing by walls in several directions till fifteen to twenty- 
five cells are present, which then separate from each other in the 
middle of the mass, and into the space so formed the secretion 
is poured. The adult gland in H. perforatum he describes as 
having a one-layered epithelium consisting of many thin-walled 
cells. 
The first advocate of the view that the cavities of these organs 
arise from absorption of cells was Link, who wrote in 1843. 
He says the glands originate as masses of tissue. Later, in 
1872, Martinet published an elaborate paper in the * Annales des 
Sciences Naturelles.’* In this he draws attention to what he calls 
the phenomenon of resorption, describing it in detail as seen in the 
glands of Dictamnus Fraxinella and in those of various species 
of Citrus. Speaking of the formation of these latter bodies, he 
says they arise as a group of thin-walled cells, smaller than the 
surrounding tissue, and having very granular contents. The 
gland so originating grows, and the component cells also grow, 
compressing the tissue. Then absorption of the cells commences 
at the centre of the nearly spherical mass, and advances slowly 
to the periphery. He says the glands of Hypericum are analogous 
to those of Citrus, and that their cavities are formed in precisely 
similar manner. In dealing with the dark glands, he says that 
these, like the others, produce an essential oil, being here at 
variance with Von Hóhnel, who says the contents of their cells 
are solid. 
The lysigenous view is also taken by De Bary (Anatomie, 
p. 218). 
In considering the results of my own investigations into the 
* “ Organes de Sécrétion des Végétaux,” Ann. des Sc. Nat. 5° sér. vol. xiv. 
