534 
PROFESSOR W. C. WILLIAMSON ON THE ORGANIZATION 
the shorter radiating branches given off* from the entire length of the tube, there is 
a special basal series, fig. 86, c, much longer and less freely supplied with secondary 
ramifications than is the case with the upper ones. These basal branches appear to 
be similar to the upper ones in their general features and origin, those radiating from 
each central tube forming a system independent of the corresponding ones given off 
by its neighbours. They interlace most freely, enclosing the endosporium in a perfect 
network of superficial ramifications, but I have not been able to detect a single 
example in which they anastomose with those of the surrounding similar systems of 
tubes. 
We obtain further light on this subject from fig. 87, which represents a portion of a 
macrospore from the same strobilus, but which has been intersected vertically. The 
drawing exhibits the bases of three of the tubular spines, b, b', and V", the two 
former being the principal ones in focus. The spines have been cut through longi¬ 
tudinally and tangentially, so that we look into their interior, which is very large in 
comparison with the thickness of the enclosing tube-wall. The spine, V ", lies deeper 
in the section, which has only sliced off a little of its base. At c we have one of 
the large basal branches of b. We now see that it gives off short, thick, lateral 
branches, cl, in every direction, downwards as well as upwards. These branches sub¬ 
divide by repeated dichotomisations, each of the secondary and subsequent branches 
being very short. Hence each of these secondary branch-systems constitutes a 
dense tuft of hollow tubes, whose repeated and peculiar ramifications remind us of 
the characteristic branching of a tuft of the well-known sea-weed, Cliondrus crispus, 
only in the case before us the ultimate subdivisions are so fine that we fail to trace 
their individual outlines where they interlace with those of the neighbouring tufts. 
This condition probably explains the nature of the network shown in fig. 43, and referred 
to on page 513 of the memoir. The lateral branches, e, given off from each spine become 
rapidly shorter as we ascend, but in all those above the basal series, c, we find the 
ternary clusters of branches to be more numerous and more closely crowded together 
than in these basal ones ; in other respects they present no differences. There is in 
them the same succession of curvilinear dichotomisations as before. The consequence 
is that the primary spines and their secondary branches are closely invested by a dense 
interlacing network of these ramifications. In the earlier part of the memoir I suggested 
the probability that these tubes had been invested by a plastic substance, in which the 
ultimate ramifications of the tubes distributed themselves. I am now satisfied that 
whatever may have been the case with the immature macrospores the matured ones 
were not so invested. What gave that appearance was merely the imperfectly preserva¬ 
tion of the minute extremities of these ramifying tubules. We have at c", in fig. 5, the 
intersected portions of other branches corresponding to c, but emanating from other 
spines. 
Whilst these portions of the organism are now interpreted without difficulty, other 
features of the structure become less easy of explanation. Proceeding upon the 
