ISOLATED INDEPENDENT CELLS. 67 
CLASS I. 
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. According to Vogel’s description 
(Physiologisch-pathologische Untersuchungen tiber Hiter, &c. 
Erlangen, 1838), the lymph-corpuscles appear to be cells, 
although he does not express the fact in words. For ex- 
ample, after the corpuscles have been exposed to the action of 
acetic acid, a nucleus is brought mto 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-cor- 
puscles, delineated in the above-mentioned work (fig. 4 6) 
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 
