QUARTERLY CHRONICLE Ot MICROSCOPICAL SCIENCE. 187 



nective tissue ; and this is advocated by M. Oilier, who cites, 

 in support of his views, the success obtained by him in pro- 

 ducing cicatrisation by means of a graft of periosteum. He 

 might also have added the clinical observation of Howard, 

 Avith his muscle grafts, as at least opposing the theory of 

 Reverdin. 



" Probably the matter would be much more easily solved 

 did we know the mode of growth of the ordinary epithelium. 

 We might then be able to ascertain the difference between 

 the formation of ordinary and cicatricial epithelium ; and we 

 would also be better able to ascribe the correct theory to the 

 production of the cicatrix from the grafts. Dr. Otto Weber, 

 long ago, stated that he had seen new cells emanate from 

 connective tissue corpuscles of granulating surfaces. Again, 

 many believe that the epidermic and epithelial cells are 

 derived from the primitive embryonic cells, and that each 

 must be derived from its parent by division of its nucleus ; 

 and several observers state that they have seen cells actually 

 undergoing a process of subdivision. The view of Reverdin 

 has been accepted by many j but we think that there is some 

 other cause, some other influence or agency at work in pro- 

 ducing the cicatrix from the islets instead of the mere presence 

 of a ' mould.' It finds no homotype in the animal body. " 



V. The Connective Tissues.— 1. Parenchymatous canals. — 

 Arnold (' Centralblatt,' 1874, No. 1, p. 1) describes a system 

 of fine parenchymatous canals in the tongue and web of the 

 foot of the frog, the relation of which to the saftcanalchen of 

 Recklinghausen and to the connective tissue corpuscles he 

 proposes further to discuss. 



2. Connective tissue of insects. — Graber (' Schultze's 

 Archiv,' x, p. 124) describes a sort of fibrilloid connective 

 tissue in the integument of insects, and its importance in 

 suspending the tracheae. 



3. Development of hone. — Kolliker's most recent contribu- 

 tions to this subject are thus summarised by Dr. Klein in the 

 * London Medical Record ' (p. 482, 1873) : 



" 1. The tijpical absorption of bone tissue. — The doctrine of 

 the normal absorption of bone tissue by osteoclasts (myelo- 

 plaxes), in the Howship's absorption-lacunse, brought for- 

 ward by Kolliker,! has been lately contradicted by Strelzofi", 

 who found that bone-tissue, once formed, is never absorbed 

 again, but grows interstitially. In the present paper Kolli- 

 ker brings forward some new facts to meet these objections. 

 At the diaphysal extremities of long bones, the external ab- 

 sorption attacks first the periosteal portion of the bone-cortex. 

 1 ' Quart. Journ. Mic. Sci.,' 1873, p. 89. 



