344 
PROFESSOR W. WILLIAMSON ON THE ORGANIZATION 
Viewing them in this light it is easy to understand the cohesion of all these clusters 
As grandmother cells of spores, they had not reached the stage of development 
at which they would be free from them attachment to the other cells ol the cluster 
in one of which they had been specially developed. If this is a correct explanation 
of these objects, the small spheres, f seen in figs. 43, 44, and 45, become groups 
of free cells, each one of which would in turn have developed within its cavity, 
by subdivision of its protoplasm, a cluster of 4 microspores, like those seen in figs. 
49, 50, and 51. On comparing the size of these latter objects with the small spheres,^, 
of figs. 43, 44, and 45, it will be seen that a very moderate measure of further 
development would bring them up to the dimensions of the group of four perfect 
microspores. I presume that when they reached this stage of growth all the barren 
cells, d and g, would have disappeared. I have already observed that in all the 
specimens of Lepidostrobus which I have examined in which the spores have attained 
to maturity, each male sporangium is crowded with microspores, but it shows no 
traces of the mother cells whence those spores were derived. In like manner the 
mother cells of macrospores are as invariably wanting. Hence the existence of 
numerous barren cells in this Lepidostrobus in such a perfect state of preservation 
indicates that we probably have before us a strobilus in an early stage of its develop- 
ment, whatever may be the true nature of its tetrasporal contents. If these tetra- 
spores are merely the grandmother cells of microspores, the small cells seen in figs. 42, 
43, and 44, being their true mother cells, then we have the materials capable of 
supplying the enormous number of spores seen alike in the microspores of the bisexual 
Selaginellse and the ordinary spores of the Lycopodia. If, on the other hand, they 
are true, and fully grown, spores, belonging to plants of the unisexual type, their 
magnitude distinguishes them conspicuously from all known similar spores, whether 
living or fossil. 
I have already stated that numerous macrospores of a very remarkable character 
have been found near Halifax by Mr. Binns, Mr. Spencer, and Mr. Earnshaw, 
associated with the spores already described. I am far from certain that all these 
belong to the same plant, but I think there is reason to believe that fig s. 58 to 66 
do so ; of these figs. 58, 59, and 60, 65 and 66 are enlarged 43 tunes ; 61 and 62, 100 
times ; and 63 is enlarged 214 times ; fig. 64 is enlarged 50 diameters.* Fig. 60 is the 
specimen which I first discovered ; subsequently Mr. Binns forwarded to me the 
examples drawn in the other figures just referred to. Shortly after these drawings were 
made Mr. Spencer sent me a series of five sections, as well as many more at a later 
date, which were of material service to me in studying these objects. 
Many of the examples consist of a double spore-wall. The outer layer is thick and 
variously furnished with peripheral radiating appendages. It exhibits no sign of 
* It would have been more convenient had all these figures been drawn to the same scale, but this 
plan would either have left the smaller ones too indefinite, or would have caused the larger ones to occupy 
too much space. 
