120 CELL THEORIES. 
important point to determine how far the passage 
of substances through that membrane was the 
result of mere osmosis, and how far it depended on 
the action of some attractive power within. To the 
school whose tendency was to refer everything to 
the laws of dead matter, the cell-wall was a most 
important agent; to those on the other hand who 
considered that to account for the formative changes 
in living bodies the presence of another force must 
be assumed, the nucleus as situated in the interior 
seemed the source of vital actions. 
Moreover, in the absence of a defined know- 
ledge of the protoplasmic element, the conception 
of the nucleus was obscured by extending the 
designation to bodies which ought not to be so 
named. An instance of this may be found in 
the case of connective-tissue-corpuscles. Many 
years before Virchow’s researches threw a light 
on these structures, a corpuscular element was 
recognized as present in connective tissue. It 
was even taught by some to be the same ele- 
ment as could easily be demonstrated as consti- 
tuting, in a cellular form, a large part of the bulk 
of foetal connective tissue, and to be of the utmost 
importance in its vital properties. But that element, 
in the adult, was known only as it may be found 
figured by Dr. Sharpey in 1848 (Quain’s ‘Anatomy,’ 
