Setentific Intelligence—Zoology. 197 
been supposed, but by division of a previously single object. Certain 
objects, called by the author primitive discs, exhibit an inherent con- 
tractile power, both when isolated, and when forming parts of a larger 
object; an incipient epithelium-cylinder having been observed by 
him to revolve by this means. Molecular motions are sometimes 
discernible within corpuscles of the blood. The author has noticed 
young blood-corpuscles, exhibiting motions, comparable to the mole- 
cular, and moving through a considerable space; and he has met 
with the nuclei of blood-corpuscles endowed with cilia, revolving and 
performing locomotion. In his first paper on the Corpuscles of the 
Blood, he described certain instantaneous changes in form which he 
had observed in blood-corpuscles, and afterwards expressed his belief, 
that these changes were referable to contiguous cilia, although he 
had not been able to discern any such cilia. He now states that 
subsequent observation inclines him to think that these changes in 
form arise from some inherent power, distinct from the motions oc- 
casioned by cilia. The primitive disc, just mentioned, seems to cor- 
respond, in some irfstances, with the “ cytoblast” of Schleiden. Thus 
the very young corpuscle of the blood is a mere disc; but the older 
corpuscle is a cell. The author minutely describes the mode of origin 
of the pigmentum nigrum ; shewing that it arises in a similar man- 
ner in the tail of the tadpole, and in the choroid coat of the eye. He 
had before described the Graafian vesicle as formed by the addition 
of a covering to the previously-existing ovisac: this covering, he 
afterwards stated, becomes the corpus luteum. He now confirms 
these observations, with the addition, that it is the blood-corpuscles 
entering into the formation of the covering of the ovisac, which give 
origin to the corpus luteum. The Spermatozoon appears to be com- 
posed of a few coalesced discs. The fibres of the crystalline lens are 
not elongated cells, as supposed by Schwann; but coalesced cells, at 
first arranged in the same manner as beads in a necklace. 
The author concludes with the following recapitulation :—1. The 
nucleus of the corpuscle of the blood admits of being traced into the 
pus-globule. 2. The various structures arise out of corpuscles hay- 
ing the same appearance, form, and size as corpuscles of the blood. 
3. The corpuscles having this appearance, and giving origin to struc- 
tures, are propagated by division of their nuclei. 4. The corpuscles 
of the blood, also, are propagated by division of their nuclei. 5. The 
minuteness of the young blood-corpuscles is sometimes extreme ; and 
they are to be found in parts usually considered as not being per- 
meable by red blood. 
