THE CELL-THEORY 



275 



and we should have a piece of bone exhibiting every variety of lacunjE, 

 from those without distinct walls to those which constitute regular 

 stellate " bone corpuscles." Finally, in bone, the formation of the 

 " Haversian spaces " of Tomes and De Morgan is a process of vacuo- 

 lation, strictly comparable to that which we have described as giving 

 rise to the areolated connective tissue. Cancellated bone is, in fact, 

 areolated osseous tissue. Once having comprehended the fact that 

 the periplast is the metamorphic element of the tissues, and that the 

 endoplast has no influence nor importance in histological metamor- 

 phosis, there ceases to be any difficulty in understanding and admitting 

 the development of the tubules of the dentine 

 and the prisms of the enamel, without the ^ 



intervention of endoplasts. These are but 

 extreme and obvious cases in which nature 

 has separated for us two histological elements 

 and two processes, which are elsewhere con- 

 founded together. 



One of the most complicated of tissues is 

 striped muscle, yet the true homology of its 

 elements seems to us to become intelligible 

 enough upon these principles. Dr. Hyde 

 Salter has pointed out.^ that in the tongue 

 the muscles pass directly into the bundles of 

 the submucous connective tissue which serve as 

 their tendons. We have figured such a tran- 

 sition in fig. 6. The tendon A may be seen 

 passing insensibly into the muscle B, the 

 granular sarcous elements of the latter ap- 

 pearing as it were to be deposited in the 

 substance of the tendon (just as the cal- 

 careous particles are deposited in bone), at 

 first leaving the tissue about the walls of the 

 cavities of the endoplasts, and that in some 



other directions unaltered. These portions, which would have 

 represented the elastic element in ordinary connective tissue, dis- 

 appear in the centre of the muscular bundle, and the endoplasts 

 are immediately surrounded by muscle, just £fs, in many specimens 

 of bone, the lacunae have no distinguishable walls. On the 

 other hand, at the surface of the bundle the representative of the 

 elastic element remains, and often becomes much developed as the 

 sarcolemma. There is no question here of muscle resulting from the 



' Art. 'Tongue,' Todd's Cyclopjedia. 



T 2 



CoDtinuily of muscle with 

 connective tissue from 

 the tongue of the lamb. 



A, Connective tissue ; 



B, muscle. 



