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 liber Eiter, &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 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-cor- 

 puscles, delineated in the above-mentioned work (fig. 4 /;) 

 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 



