4 HISTO-CHEMISTRY. 



We need hardly remark, in connexion with these histological 

 objects, that the chemist has to deal solely with the elementary 

 tissues ; for the coarser or finer admixture of cells, fibres, &c., 

 which we find congregated even in the tissues still deemed simple 

 by many histologists, cannot in themselves constitute the object of 

 a chemical investigation ; we should, for instance, regard it as 

 altogether inexpedient to devote special sections of this volume to 

 the consideration of the smooth muscular fibres of the intestine, 

 the contractile tissue of the tunica dartos, the middle arterial 

 coat, &c. We know that these tissues are composed of very vari- 

 ous histological elements, and that there occur in them, interwoven 

 in many forms and proportions, fibres of connective tissue and 

 nucleated fibres, or ordinary elastic tissue, with the fibre-cells 

 which are common to all contractile organs. The admirable 

 inquiries of Kolliker have indeed shown us that these fibre- cells 

 constitute the most essential element in all the contractile tissues, 

 and his results have been almost as decisively confirmed by 

 chemical investigation as by the certain physiologico-physical test 

 of magnetic electricity, Hense we should not regard the middle 

 arterial coat, or even the walls of the blood vessels themselves, as 

 subjects for histo-chemical research, but we should rather attempt 

 to ascertain, under the head of " fibre -cells," the chemical character 

 of the substance that is common, and at the same time peculiar, to 

 all contractile tissues. At the present day it would be highly inex- 

 pedient to devote special sections to the chemical constituents of 

 the eye, the chemical constitution of the brain, &c. We are, how- 

 ever, as yet unable to limit histo-chemistry very strictly to the 

 consideration of the pure elementary tissues, for we must still 

 speak of nervous tissue, of the striped muscular tissue, &c., 

 although very different morphological and chemical elements are 

 associated in them ; for, unfortunately, we have not yet made suffi- 

 cient progress to enable us properly to distinguish from one another 

 the elementary parts of these compound tissues, and we are conse- 

 quently obliged to limit histo-chemistry to the mere determination 

 of the chemical characteristics of the morphological elements of the 

 tissues. 



Although every one who directs his attention to histo-chemistry 

 must be familiar with the normal histological characters of the 

 tissues, and although every one who would propose engaging in 

 histological investigations must be thoroughly familiar with the 

 present state of general anatomy, we have notwithstanding deemed 

 it expedient to introduce a sketch, short though it may be, of the 



