1881.] the Striation of Voluntary Muscular Tissue. 365 



Rutherford ("Text-book of Physiology," p. 128), who describe 

 Dobie's line as consisting of a row of dots. Engelmann, indeed, 

 describes a row of dots on either side of this line. 



Krause would have ns believe that the fibre is divided by these 

 membranes into a linear series of little boxes, each box or casket, 

 " Miiskelkastchen," containing a dark stripe with (as the membrane 

 lies in the centre of the light stripe) one half of that on either side. 

 Merkel (" Lehrbuch der Gewebelehre," Stuttgart, 1877, p. 83), to 

 make the " Miiskelkastchen " self-containing, affirms that the mem- 

 brane of Krause is double. As to the stripe of Hensen, this is by very 

 many looked upon as still another structure lying in the centre of the 

 dark stripe ; it is in many fibres very clearly to be made out, its border 

 being well defined, and in stained preparations (logwood) it has 

 decidedly a lighter tint than the rest of the stripe. Still some 

 (Krause) look upon it as an indication of the highly refracting 

 power of the dark stripe, comparing the appearance with the light 

 centre of an oil globule. The other cross striae, of which there are 

 many described by some observers, but none at all universally 

 accepted, are, as a rule, considered as indicating further complications 

 in the muscle fibre ; indeed, the "Miiskelkastchen," by most advanced 

 microscopists, although not 10 o 00 of an inch in length, consists of 

 some ten or twelve different parts. We may postpone, I think, in- 

 definitely the consideration of these details. 



While there is great unity as to the appearance of a fibre during 

 a state of rest, the changes which the fibre undergoes when passing 

 into the contracted condition are not at all understood. Not only 

 does one fail to find among histologists agreement as to the changes in 

 appearance, but the interpretations of these are as numerous as the in- 

 vestigators themselves. All are agreed, that during contraction, the 

 fibre as a whole shortens and thickens, but the changes in form which 

 the cross striae undergo are not understood so well. 



Klein, in his " Atlas of Histology," maintains the broadening of 

 both stripes transversely, the dark stripe becoming thinner in the long 

 axis, and the bright stripe more opaque. Ranvier (" Traite Technique 

 d'Histologie," p. 489) states that the only points one can conscien- 

 tiously observe in the contraction of a living fibre are, that a knot or 

 bulging forms, in which the dark bands approximate, being only sepa- 

 rated by Dobie's line. This led him to believe that the dark bands are 

 the true contracting part of the fibre. Ranvier worked especially 

 with osmic acid, fixing the fibres when at rest, and during contrac- 

 tion. W. Krause (" Allgemeine und Mikroscopische Anatomie," p. 92) 

 describes the contraction as follows : — The thickness (in the length of 

 the fibre) of the dark stripe or an isotropous substance remains the 

 same as far as can be seen, while the thickness of the isotropous sub- 

 stance, " Zwischensubstanz " becomes less. From this, he argues that 



