Miscellaneous. 395 
ded ; while others contend that the type most nearly agreeing with 
the diagnosis, or which has its characters best expressed in the name 
itself, should be regarded as the type of the original genus. 
Still others say that the first author who divides and properly 
restricts a genus originally founded upon heterogeneous materials has 
the right to determine, arbitrarily, which shall retain the old name, 
and which shall receive new ones. Now all such confusion is avoided 
by simply stating which species is recognized as the type in founding 
a new genus.—Nilliman’s American Journal, March 1866. 
The Placentoid, a new Organ of Anthers. By M. Cuatin. 
The organ now to be made known has not yet been indicated. 
The name of placentoid, by which we propose to designate it, recalls 
the analogies of form, position, and, to a certain extent, of function 
which it has with the placentas of ovaria with axile placentation. 
We shall consider it under the points of view— 
1. Of morphology or organography ; 2, of histology ; 3, of bio- 
logy ; 4, of taxonomy ; and 5, of philosophy. 
1. Morphology of the placentoids.—These organs, by the place 
which they occupy in the cells and the forms which they put on, recall 
the axile placentas of bilocular ovaria. If we make a transverse sec- 
tion of the ovary of a Solanum and of one of its anthers, we find in 
each of the cells of the latter, as in the ovarian cavity, a fleshy body 
which advances towards the middle of the chambers of the ovary and 
_ of the cells of the anther. 
In consequence of the considerable space which it occupies in the 
cells, the placentoid often greatly reduces that left for the pollen, 
nearly as, in a great many Solanaceze and Scrophulariaceze, we see 
the seeds pressed between large trophosperms and the valves of the 
pericarp. Sometimes the placentoid advances so far towards the op- 
posite valve as to touch this with its extremity, thus nearly subdi- 
viding each cell into two. The section of a young anther thus con- 
structed is subdivided into eight subcells if the anther be complete 
(Hemitomus), or into four if, as in Salvia and Westringia, the anther 
should be reduced to a single cell. Some plants (Justicia flavicoma) 
only present placentoids upon one surface of the dissepiment ; this 
organ is consequently wanting in the cell placed on the opposite side. 
Like the dissepiment, the placentoids are shaped out of the paren- 
chymatous mass of the young anther. 
The duration of the placentoids is limited ; they disappear towards 
the period of the maturation of the pollen, sometimes leaving their 
traces in the form of two small appendages approximated to the con- 
nective by the retraction of the dissepiment which bears them. 
To sum up, like the dissepiment, and even still more than this, 
the development of the placentoids is connected with that ot the 
pollen. 
2. Histology of the placentoids.—We have always found the pla- 
centoids formed by a parenchymatous tissue very similar to that which 
