236 



threads, which in many places have the appearance of a necklace, 

 but subsequently lose the traces of division, and become cylinders. 

 Schwann had conjectured that the globules just referred to — as ha- 

 ving been observed by V alentin — are cells, and that these cells coa- 

 lesce to form a secondary cell, that is, the muscle-cylinder. The 

 author confirms the observations of Valentin and the conjectures of 

 Schwann, with the addition, that the globules coalescing to form the 

 muscle-cylinder are blood-corpuscles which have become cells. The 

 fibrils appear to be subsequently formed within the cylinder, which 

 thus becomes the muscular fasciculus. The medullary portion 

 of the cylinder appears to be composed of the pellucid objects, one 

 of which is contained within each altered blood-corpuscle. Some 

 of these pellucid objects, however, continue to occupy a peripheral 

 situation. 



The author thinks it is not probable that muscular fibre and the 

 chorion are the only tissues formed by the corpuscles of the blood ; 

 he is disposed rather to inquire, how many are the tissues which 

 they do not form ? Nerves, for instance, are known to arise very 

 much in the same manner as muscle-cylinders ; and epithelium-cells 

 sometimes present appearances which have almost suggested to the 

 author the idea that the)'- were altered corpuscles of the blood. 



Schwann had prevously shown that " for all the elementary parts 

 of organisms there is a common principle of developement," — the 

 elementary parts of tissues having a like origin in cells, however 

 different the functions of those tissues. The facts made known in 

 the present memoir not only afford evidence of the justness of the 

 views of Schwann, but they farther show that objects, such as the 

 corpuscles of the blood, having all the same appearance, enter im- 

 mediately into the formation of tissues which physiologically are 

 extremely different. Some of these corpuscles arrange themselves 

 into muscle, and others become metamorphosed into constituent 

 parts of the chorion. But the author thinks it is not more difficult 

 to conceive corpuscles having the same colour, form, and general 

 appearance, undergoing transformations for very different purposes, 

 than to admit the fact made known by two of his preceding me- 

 moirs,- — namely, that the nucleus of a cell, having a central situa- 

 tion in the group which constitutes the germ, is developed into the 

 whole embryo, while the nuclei of cells occupying less central situa- 

 tions in the group, form no more than a minute portion of the am- 

 nion. It is known that in the bee-hive a grub is taken — for a spe- 

 cial purpose — from among those born as workers, which it perfectly 

 resembles until nourished with peculiar food, when its developement 

 takes a diflferent course from that of every other individual in the 

 hive. 



The Society then adjourned over the Whitsun Recess, to meet 

 again on the 18th instant. 



