ON THE STRUCTURE OF MUSCULAR FIBRE. 251 



may be compared with the nuclei of the flat cells in the inte- 

 rior of the membrane, which are shown beside them. The 

 branched cells shown are in an early stage of development. 

 Their further development does not consist in increase of 

 size, but in absorption of the protoplasm which surrounds 

 the nucleus and the conversion of the stained granular-looking 

 processes into delicate glistening threads, which are incapable 

 of staining, but which may be sometimes recognised in 

 osmic-acid preparations examined in solution of acetate of 

 potash. 



The conclusion to which I have therefore come is, that the 

 " cellules vaso-formatives " of Ranvier are spaces in the 

 omentum, to which I submit the term *'cell" is not 

 applicable. 



The development of blood-vessels takes place by an escape 

 of, first, the fluid, and finally of the formed elements of the 

 blood, from the vascular system into those spaces. The esta- 

 blishment of the blood current is speedily followed by the 

 formation of a membranous wall around the current, which 

 is impermeable for an injection mass or the blood, and the 

 process is complete. My previous observations on the growth 

 of vessels in foetal and in inflamed tissue are therefore in har- 

 mony with those made on the omentum, and recorded in this 

 paper. 



On the Structure of Muscular Fibre. By G. Thin, 

 M.D. (With Plate XV, figs. 6—14.) 



In order that the value of the preparations which it is 

 the object of this paper to describe may be properly estimated 

 it is necessary to refer the reader to a paper I published in 

 'The Edinburgh Medical Journal' for September, 1874, On 

 the Minute Anatomy of Muscle and Tendon, and especially to 

 the figures by which it is illustrated. For the sake of 

 completeness I will, however, give here a short summary 

 of the results of my investigations up to the time when that 

 paper was written. 



In stained transverse sections of muscular fibres of the 

 frog, which had been carefully hardened in weak solution 

 of chromic acid without any further hardening by alcohol, 

 Cohnheim's fields were seen to contain about twelve to fifteen 

 fibrillffi. The fibrilla was recognised both in chromic acid 

 and in gold preparations as an exceedingly fine cylin- 



