Page:Microscopicial researchers - Theodor Schwann - English Translation - 1947.pdf/93

ISOLATED INDEPENDENT CELLS.

By the above term we understand cells which either float free in fluids, or, at least, are moveable, though lying in close contact. Such cells, therefore, possess the highest degree of individuality. This class includes the cells of lymph, blood, and the various secretions. The ovum might be placed at the head of this class in a system of general anatomy; but the plan of the present work required that it should be discussed previously.

1. Lymph-corpuscles. Accordig to Vogel’s description (Physiologisch-pathologische Untersuchungen über Eiter, &c. Erlangen, 1838), the lymph-corpuscles appear to be cells, although he does not express the fact in words. For example, after the corpuscles have been exposed to the action of acetic acid, a nucleus is brought into view, the production of which I do not suppose to be referrible to a separation into envelope and nucleus, but believe it to have been previously formed, and rendered visible solely in consequence of the greater degree of transparency acquired by the envelope, i. e. the cell-membrane, and its contents, from the action of the acid upon them. One of the nuclei, amongst the lymph-corpuscles, delineated in the above-mentioned work (fig. 4 b) appears to contain a nucleolus in its centre. I have not made any researches myself upon this subject. The mode of production of the lymph-corpuscles has not as yet undergone investigation. They are probably formed in the lymph-plasma, which serves as their cytoblastema, in accordance with the general law before laid down. We cannot as yet decide the question whether the nuclei are present before the cells, and whether the latter are first formed around them; perhaps the small granules which Vogel delineates from lymph are young nuclei.

2. Blood-corpuscles. C.H. Schultz was the first who proved