DEVELOPMENT OF THE SPOROGONIUM IN THE MOSSES. 275 
8. Note on the Nomenclature of the Central Strand. 
A paper has recently appeared by Haberlandt (7) on the 
anatomy and physiology of Mosses. In regard to what he has 
said about the sporophore, I think it will be useful to make a few 
remarks, 
On the whole, Prof. Haberlandt’s observations and my own 
are in agreement; but he does not seem in all cases to have 
determined the limits of the outer cylinder and the parenchy- 
matous sheath. 
Prof. Haberlandt has called the tissues of the central strand 
of the seta by the same names that he has given to the several 
parts of the vascular bundle in the Vascular Plants ; namely, the 
axial solid cylinder of thin-walled cells the Hadrom strand, and 
the outer hollow cylinder the Leptom cylinder. The terms 
Hadrom and Leptom were first used by Haberlandt (7) in 1884 
to designate the wood (xylem) and bast (phloém) of the Vascular 
Plants ; and there would have been no objection in so using them 
for the tissues of the central strand of the seta (sporophyte) so 
long as they were not used also for the conducting tissues of the 
oophyte; but unfortunately Haberlandt has used them for both 
Purposes, so that henceforth these terms cannot be applied so 
as to to have a strictly morphological meaning. Consequently, 
although it had not originally been my intention to do so, I 
thought it best to adopt some terms for the tissues which I 
have described above which should have a fixed and definite 
Morphological meaning. As every one will admit that the 
tissues of the sporophyte of the Muscinew are homologous 
with those of the sporophyte of the Vasculares, even if they also 
consider them to be homologous with other structures, the terms 
Leptoxylem and Leptophloém have been adopted to designate 
the water-conducting * and organic-material-conducting tissues 
respectively of the sporophyte only of the Muscines. — 
The prefix lepto (Aeros, meaning thin, slender, insignificant) 
has been used for scientific purposes to indicate rudimentariness of 
structure in, for example, the name * Leptocardia, t and again in 
* On the function of this tissue see my note on the subject elsewhere (26). 
+ Leptocardia, a class of the Chordata in the Animal Kingdom, partly cha- 
Facterized by having a very rudimentary heart. 
