82 THE ROYAL SOCIETY OF CANADA 



Bles's fluid was found to be by far the most satisfactory. I had 

 previously discovered that this material was ideal a a fixative for 

 such delicate membranes as the retina, and I gave its composition 

 in a paper dealing with the development of that structure (Jour, of 

 Anat. and Phys., Vol. 39, 1905, p. 138). As the virtues of Bles's 

 fluid are apparently still known only to a few embyrologists, it will 

 not be out of place to again give its formula which is as follows: — 



70 per cent, alcohol 90 parts 



Glacial Acetic Acid 3 



Formalin (40 per cent. F.A.) 7 



It was found to be absolutely essential that the tissues be fixed 

 whilst in the living condition, for it is well known that muscle sub- 

 stance is one of the first to exhibit post mortem changes. I would 

 suggest the latter as one explanation of the degenerative changes 

 described in developing muscle tissue by Mayer, ^ Barfurth^, Bardeen^ 

 and Godlewski*, though there is another, as I will show in Part IV 

 of this memoir. On the other hand the contraction difficulty had to 

 be contended with. It was discovered, however, that Bles's fluid 

 caused unequal contraction; some parts of the same muscle mass 

 showing a condition of rest or even relaxation. Fig. 1 which was 

 microphotographed from a particularly lucky specimen, is magnified 

 3,000 times, and yet shows the various sarcous elements as clear as in a 

 drawing. A week's immersion in this fluid was found sufficient to 

 completely fix embryonic muscle tissue. 



III. The Staining Reagents Used 



The next difficulty proved to be the selection of a suitable stain. 

 In this case, again, a great deal of experimenting had to be carried 

 out. It is a well recognized fact that striated muscle does not react 

 freely to ordinary dyes, and yet it was essential that the sarcous 

 elements should stain of an intensity sufficient to produce a satis- 

 factory microphotograph. My labours were rewarded by discovering 

 a modification of the iron-alum-haematoxylin stain which satisfied 

 in a remarkable manner all the requirements of the case. The mode 

 of application of this will be found fully described in a previous com- 

 munication (Jour, of Anat. and Phys. Vol. 39, 1905, p. 139), so that a 

 further description will not be necessary here. It will therefore be 

 sufficient to state that the sarcous elements of Bowman exhibit the 



'Biolog. Centralblatt, Bd. IV., 1884. 

 «.■\rchiv fur mikros. Anatomic, Bd. XXIX, 1887. 

 3Johns Hopkins Hosp. Reports, Vol. IX, 1900. 

 ^Archiv fur mikros. Anatomic, Bd. LX, 1902. 



