178 QUARTERLY CHRONICLE OF MICROSCOPICAL SCIENCE. 



stance," makes its appearance between them. This, liowevei*, 

 is simply fluid, and differs from ordinary serum only in 

 containing mucin, in addition to its ordinary components. 

 Boll regards it as a transudation from the vessels, and in its 

 amount proportional to their development. It has, there- 

 fore, simply a local relation to the cells. 



About the seventh day and a little later the formation of 

 fibre is extended over the whole cell, and single fibrillar may 

 then be traced from one end to the other of the cell, and 

 further still outside it, even running by or through three or 

 four embryonic cells. It appeared most probable that this 

 results from the union or fusion of the several divisions 

 formed in different cells, not by the excessive development 

 of a single one. Beside these longitudinal fibres there are, 

 however, transverse ones, which unite adjacent cells to one 

 another. No spontaneous movements or changes of form 

 were ever seen in the lines of granules situated between the 

 fibres, and Boll, therefore, concludes that the amoeboid pro- 

 perties of the residual protoplasma no longer exist after the 

 commencement of fibrous metamorphosis. Further, in ac- 

 cordance with this .negative result, it was observed in later 

 stages of development that these interfibrillar masses of 

 granules remain isolated from the rest of the protoplasma of 

 the cell. 



Since the fibrous transformation of the embryonic connec- 

 tive tissue cells begins at a time when the vessels are very 

 scantily developed, the latter cannot be regarded as having 

 any determining influence upon the process. On the other 

 hand, as soon as the first set of vessels is formed. Boll 

 believes that most of the connective-tissue-cells actually 

 arise from vessels. He arrives at this conclusion from the 

 very great abundance of vessels in the tissue, from the large 

 number of migratory cells which are attached to them, and 

 finally from the circumstance that the formation of fibres 

 takes place earliest and most vigorously in the adventitia, and 

 gradually spreads thence towards the centre. After the 

 tenth day numerous minute fatty molecules appear, both in 

 the connective-tissue- cells and in the migratory cells, which 

 gives to the central (still protoplasmatic) portions more and 

 more the aspect of granule-cells. The cells, at the same 

 time, come into closer contact with one another, the inter- 

 cellular substance disappearing till, on the seventeenth day, 

 it is hardly to be seen. 



Quite similar conditions may be traced in the subcutane- 

 ous tissue of the scalp and of the extremities. Here, how- 

 ever, the intercellular fluid is never so abundant as in the 



