910 PROFESSOR W. C. WILLIAMSON AND DR. D. H. SCOTT ON THE 
sporangium appears to be filled with parenchymatous tissue.* These apparently 
parenchymatous sporangia are sometimes associated in the same strobilus with others 
which show the lining tissue only.t 
It is a question whether such sporangia are ever really filled with tissue, or whether 
the sections may not in these cases be tangential to the sporangium, so as to pass 
through the lining layer, without reaching the spores within. This is a possible view, 
but we do not think that all these instances can be thus explained. The sporangia 
with parenchymatous contents cannot represent a normal early stage of development, 
for they occur side by side with others in which the spores are fully formed, and in 
which there is often no trace even of the lining tissue. On the whole we are disposed 
to regard all the structures in question as representing more or less completely 
abortive sporangia in which either the whole, or the outer portion only, of the 
sporogenous tissue has remained sterile. This view is supported by the relatively 
small size of those sporangia which appear to be completely filled with parenchymatous 
tissue. 
D. The Spores. 
It has long been known that the spores of Calumostachys are often found associated 
together in tetrads, each tetrad being enclosed within a common membrane, which is 
doubtless the wall of the mother-cell. Cases of this kind have been figured in previous 
memoirs,{ and have also been observed and figured by M. Renautr in allied 
fructifications.§ The latter author lays great stress on the arrangement of these cells 
in tetrads, regarding this fact as an argument for the bodies in question being of the 
nature of pollen-grains, rather than spores. | 
In Calamostachys Binneyana, at any rate, there is no ground for such a view, for the 
spores certainly did not remain associated in tetrads when mature. Isolated spores 
are just as common as tetrads, and sometimes occur together with them in the 
same sporangium (see Plate 81, fig. 33), while in other cases the whole sporangium 
is occupied by isolated spores. The separation of the sister-spores from one another 
must have taken place relatively late, but it certainly happened before maturity. 
We have paid special attention to the spore-tetrads, which are shown on various 
scales, in Plate 81, fig. 33, and Plate 82, fig. 34. In some cases the group of four 
spores is perfectly normal, all four being of approximately equal size (fig. 34, A). 
Very often, however, the spores of the same tetrad are of extremely unequal dimen- 
* An example of this has been previously figured ; see Wittiamson, “Organization,” Part X., Plate 16, 
fig. 18. 
+ As is the case, for example, in C.N. 1008, and 1898 A. 
{ WitttaMsoy, “ Organization,” Part V., Plate 7, fig. 43, Part X., Plate 15, fio. 17, 
§ Bg. in his Bruckmannia Grand’ Huryi, ‘ Ann. Sci. Nat., Bot.,’ Sér. 6, vol. 3, Plate 3, Fig. 7. 
|| ‘Comptes Rendus,’ vol. 102, March 15, 1886. 
{| See Wititamson, “ Organization,” Part V., Plate 6, fig. 7 (C.N. 989). 
