86 INTRODUCTION. 



only; for all are areolar and permeable more or less distinct, 

 all are more or less compound, 



85. This first view of the subject is not sufficient to show 

 the exact texture of the solid parts. By a closer examination, 

 we perceive that these apparent fibres, these membranous layers, 

 these granulations, are themselves compound; and as the solids 

 contain the humours, it has been generally believed, that there 

 is nothing but vessels in the solids. This erroneous idea, for 

 the vessels themselves, are compound parts, has been recently 

 revived in a posthumous work of Mascagni. Other authors 

 have admitted that every thing is formed of the cellular tissue, 

 and this by interwoven layers and fibres, or by cells or vesi- 

 cles adhering to each other. But, the cellular tissue, although 

 it is the principal element of all the parts, is not the only 

 one. As to the idea of a parenchyma, as abase or generating ele- 

 ment of all the solids, it is an extremely vague one, and about 

 which we have not been able to agree. Haller,* besides the 

 cellular tissue formed by the reunion of fibres and layers, and 

 which is the most common and extensive, has admitted in the 

 composition of the organs the muscular fibre and medullary 

 substance. This division, with some slight modifications 

 more or less happy, has been since generally adopted. Thus 

 Walther admits a cellular or membranous texture, a fibrous 

 or vascular one, and a nervous one; Pfaff a vascular structure, 

 a fascicular and a cellular one; others a cellular, a vascular 

 and a massive one, or one without cells and vessels. M. Chaus- 

 sier has added to the three elementary parts of Haller a fourth 

 fibre under the name of albugineous fibre : it is the base of the 

 ligaments; M. Richerand has superadded the epidermoid or 

 horny substance. Among the twenty one tissues admitted by 

 Bichat, there are three which he considers as generators of 

 the others : they are the cellular, the vascular and the nerv- 

 ous. M. Meyert admits, also three elementary organs: 1st, 

 the cell, the vessel or the gland; 2d, the irritable cellular or 

 muscular fibre; 3d, the sensible fibre or the nerve. 



* DC. corporiti huinuni fabrica et fimdianibus. Tom. 1. Lib. 1. sect. iii. 

 f Ueber hutologie, &c. Bonn, 1819. 



