86 Dr. Barry's renewed Inquiries concerning the 



functions rendering it in importance second to none. In muscle, 

 this substance, hyaline, is often found within the winds of the 

 spiral threads ; often the fibril is enclosed within a cylinder of 

 hyaline, fig. 3. It is very important to be aware of the little 

 difference in refractive power between the hyaline and the sub- 

 stance of the spirals, whereby the outline of the latter becomes 

 almost invisible. This is especially the case when the fibril still 

 lies in the primitive fasciculus, and even occurs after its separa- 

 tion from it. Hence the different views taken by observers of 

 the fibril, especially that assigning to it a structure comparable 

 to a row of varicosities or beads. It is therefore equally import- 

 ant to apply reagents that will serve to introduce a greater dif- 

 ference in the refractive power of the two substances in question, 

 and thus diminish the misleading influence of the hyaline. 



This hyahne appears in another way to have misled observers. 

 "Where contained within the winds of spiral threads, fig. 6 a, it 

 holds together a row of cell-germs ; which cell-germs, on the 

 wearing out as contractors of the old spiral threads, give the 

 material for new ones. And some observers, overlooking the 

 spiral threads, probably mistook such rows of cell-germs for 

 fibrils. This mistake is very likely to be made when the muscle 

 has undergone a slight degree of decomposition, fig. 6 b, whereby 

 the spiral threads dissolve and disappear sooner, leaving exposed 

 the axis of hyaline with its row of cell-germs. Prof. Bowman 

 appears to have figured such an axis of hyaline containing cell- 

 germs, as a fibril*. It may appear absurd to suppose that any 

 doubt on such a matter can be entertained ; and yet, since the 

 mistake in question has been made, the author ventures to ask 

 physiologists which appears to them the more probable : that 

 spirals are formed first in order to produce cell-germs (!), or that 

 cell-germs are first formed in order that they may give origin 

 to spirals ? c and d in fig. 6, show division and subdivision of 

 the cell-germs for the production of minuter spirals. It must 

 be admitted that the changes in the structure of the fibrils, 

 attending then* continued composition or decomposition, present 

 a series of transition states such as may mislead all engaged in 

 this most difficult field of observation. 



It is known that in some states the primitive fasciculi during 

 manipulation break off short, that is transversely, and that in 

 other states they divide in a longitudinal direction ; but it is not 

 known on what this difference depends. The author explains it 

 thus : — He finds the tendency to transverse cleavage to be in 

 proportion to the amount of contraction the muscle happens to 



* Cycloiifcclia of Anatomy and Physiology, aiiicle " Muscle and Muscular 

 Contraction," fig. 287 c. In his earlier work, Phil. Trans. 1840, no such 

 figure is to be found. 



