THE CELL DOCTRINE. 23 



ules. In the year 1801, the philosophic mind of 

 Bichat elaborated his excellent classification, but 

 he seems to have made no original investigations in 

 minute structure, or to have adopted any special 

 theory of an ultimate physical element. The bro- 

 thers Joseph and Charles Wenzel,* in 1812, de- 

 scribed the brain as composed of globules of small 

 size. Among the earliest histologists worthy of 

 mention, is Treviranus,f whose elements, according 

 to Henle, were first, a homogeneous, formless matter; 

 second, fibres; third, globules (kiigelcheu). Mr. 

 Bauer,| quoted as a most experienced microscopic 

 observer by Sir Everard Home, in 1818, and again 

 in 1823, described the ultimate globules of the brain 

 and of muscular fibre as of the size of a globule 

 of blood when deprived of its coloring matter, or 

 about o Vou f an men m diameter. The fibre was 

 excluded as an ultimate element of organization 

 by Heusinger in 1822-4, who started all tissues 

 from the globule, still, however, retaining the form- 

 less material of Haller and Trevirauus. Heusinger 

 formed the fibre by the linear apposition of his 

 globular elementary parts, and even explained how 

 canals and vessels were formed by a similar ar- 

 rangement of vesicles \vhich had originated from the 

 globules. The account given by Henle|| of the 

 method in which Heusinger built up his fibres and 

 vessels is interesting, and is worth translating, since 



* Wenzel, op. citat., p. 24. f Treviranus, op. citat. 



J Bauer, op. citat. Heusinger, op. citat., p. 112. 



|| Henle, Allgemeine Anatomie. Leipzig : 1841, p. 128. 



