1881.] 



the Striation of Voluntary Muscular Tissue. 



373 



and on examination, what was my surprise to find that in some of 

 them the light stripes (valleys) were most brilliantly stained with 

 carmine. I was long puzzled at this, when it was at last discovered 

 that the picro-carmine had dried somewhat on the preparation, and 

 the carmine had mechanically precipitated along the valleys, filling 

 them up. At the end of one or two fibres this precipitation had 

 partially peeled off, showing undoubtedly the true nature of the phe- 

 nomenon. 



I have in my possession very beautiful alcoholic preparations stained 

 with logwood. At first sight, from a study of many of the fibres, one 

 would be led to believe that the bright stripe is wholly unstained, 

 while the dark stripes are of a beautiful violet. 



A careful examination, however, reveals the fact that such fibres 

 are broken up transversely, looking like piles of coins, a very common 

 occurrence, especially in preparations that have been long mounted. 

 The coins, lying close to one another, with narrow chinks between, of 

 course revealed transverse unstained tracts, which could well be mis- 

 taken for the bright stripe. 



More interest and discussion has hitherto accrued to the action 

 of muscle on polarised light, than to the effects of staining reagents. 

 We have seen that much difference of opinion exists : Briicke has 

 maintained that not only is the dark stripe (ridge), as all are agreed, 

 doubly refracting, but that the whole of the light stripe is isotropous. 

 I myself was led to modify this, discovering that on careful focussing 

 with a fibre not at all sheared in its length, the central part of the 

 light stripe was undoubtedly anisotropous. This I have afterwards seen 

 figured, as before mentioned, in Hermann's " Physiology," and have 

 introduced the diagram into fig. 2. It is a point of some practical 

 difficulty to mark exactly the positions of the cross bands while turning 

 the analyser, and thus changing the character of the field. This 

 difficulty has been overcome completely by a suggestion of Professor 

 Tait's, who has helped me much in this part of the work. Very fine 

 emery powder should be sprinkled over the preparation before covering 

 it ; for then, on examination, numberless little black specks will be 

 seen in the field. A cross band of a fibre is selected for examination 

 which is exactly opposite one of these little specks, then when you 

 rotate you can definitely affirm, having the little black speck for your 

 guide, what change has occurred. 



Rabbits' muscles are very satisfactory objects for examination, as 

 they do not cleave across at all readily. The adductor muscles of the 

 leg should be excised, slightly stretched on a piece of wood, and 

 placed in 50 per cent, alcohol until they split readily into fibrils. 

 They may then be mounted in any ordinary fluid, a pinch of emery 

 powder having been sprinkled over the preparation before covering. 



It is necessary to use a power of 800 or 1,000 diameters in the in* 



