of the Organs of Pilularia globulifera. 491 
facts, that the other ruptured sporules are not absorbed, and that an aperture 
in the mother-cell does actually exist at the proper place, but on account of 
the delicacy of the object it cannot be clearly ascertained until a later period 
(Tas. XXXIV. fig. 5.). The sporule now begins to assume a yellowish-brown 
hue, and a deposition of opake matter takes place on the outer surface of the 
mother-cell around the smaller extremity (Tan. XXXV. fig. 40 & 41.). This 
deposition gradually increases until the whole sporule is completely covered, 
except in some occasional instances the apex of the conical projection formed 
by the mother-cell remains uncovered (Tas. XXXIV. fig. 4 & ö.). This depo- 
sition, which forms the outer coat of the sporule, is much thicker about the 
smaller extremity of the sporule than elsewhere, and acquires at this part 
a fibro-cellular texture, as represented at Tas. XXXIV. fig. 6. When the 
outer coat is completely formed, the mother-cell or middle coat ceases to 
enlarge, whilst the inner sac or true sporule continues its growth until it is 
checked by coming in contact with the inner surface of the mother-cell, to 
which in its mature state it is firmly adherent. The sporule is at first perfectly 
pellucid and deficient of all granular contents ; it is not till after the addition 
of the outer coat that the grumous granular matter is secreted. It will be 
seen from this description, that the anatomy of the ripe sporule accords with 
what is observed to take place during its development ; and as the dissection 
of the ripe sporule occurred first in the order of my observations, this corre- 
spondence was a source of great satisfaction to me. It appears, therefore, to 
be certain that the sporule consists, in the first place, of the internal membrane 
or coat formed by the true sporule, then the middle coat formed by the 
mother-cell, and lastly, the outer testaceous opake coat, the result of the de- 
position, to which some may perhaps be inclined to add the gelatinous cover- 
ing which makes its appearance on maceration in water; but as it is not an 
organized substance, I am not disposed to consider it as a proper integument. 
As there is no evidence whatever, during the development of the sporule, of 
the internal delicate sac which is found after germination has commenced, I 
think we may safely conclude that it is the product of germination. It is 
scarcely necessary to remark, that the first-described bodies are those which 
have been considered by some botanists as the pollen, or that Dr. Lindley's 
shrewd conjecture, that they are abortive sporules, is perfectly correct. In 
VOL. XVIII. 3T 
