16 INTRODUCTION. 



passage of the secreted fluid, which is conveyed into the intestinal 

 canal or to the surface of the body. This efferent canal receives, 

 like an arterial trunk, the finer canals which effect the secretion, 

 and which are covered with epithelium. To such belong the 

 kidneys, the liver, the salivary glands, &c. 



From what has been said, it is obvious that we cannot adopt 

 that division of the Tissues which an esteemed writer 1 has pro- 

 posed: into simple, constituent, and compound tissues. Doubtless 

 every muscle contains nerves and blood-vessels, but nerves and 

 blood-vessels are not on that account constituents of muscular 

 tissue. According to our view, every tissue is simple, but it may, 

 either by itself, form special parts, or only in combination with 

 other parts. The corneous tissue is the only one which comes 

 under the first head : all other tissues form this or that part, only 

 in combination with one another : nervous tissue, for instance, does 

 not by itself form a nerve, but only in combination with conjunc- 

 tive tissue and blood-vessels. Some of these compound tissues are 

 distributed generally throughout the whole body, others are limited 

 to certain parts. To the generally distributed belong conjunctive 

 tissue, vascular tissue, and nervous tissue: the other tissues are 

 appropriated to determinate parts of the body and have a greater 

 self-subsistence, as cartilage tissue, muscular tissue, elastic tissue. 

 This was the division formerly adopted by BICHAT. Other di- 

 visions of the tissues, founded on chemical research, as into gelati- 

 nous and albuminous tissues, may have their use in Physiology, but 

 are not to be considered as anatomical divisions. 



The above tissues, then, build up the proximate organic con- 

 stituents of the animal body. Formerly, when less weight was 

 allowed to microscopic enquiry in general anatomy, the ultimate 

 organic constituents in these tissues were neglected : but now their 

 description forms a part of the description of the tissues themselves. 

 In this way we have learnt to recognise in conjunctive tissue, in 

 nerves, in muscles, &c. fibres as the ultimate elements of microscopic 

 analysis : in cartilage, round or oblong corpuscles : in corneous and 

 adipose tissues, cells. It maybe asked, whether these organic elements 

 can be deduced from one another ; or, in other words, whether all the 



1 E. H. WEBER in the 4th edition of F. HILDEBRANDT'S Itandbuch der Anatomie 

 dcs Menschen revised by him. Braunschweig, 1830. 8. s. 169 178. 



