83 Dr. Barry's renewed Inquiries concerning the 



of interlacement, throwing new light upon the whole ; and now 

 understands how it was that observers did not see what he has 

 seen. The attention of some at least appears to have been given 

 so exclusively to one or to another of those states of interlace- 

 ment, that they remained, as it were, at diflferent stages in their 

 attempts at explanation. Probably his double spiral fibril ap- 

 peared to most observers too complicated, perhaps too artificial. 

 Now, however, having found and figured transition stages extend- 

 ing to complete relaxation, he hopes that there will be some at 

 least disposed to rejjeat their examinations, and with more mi- 

 nuteness than before. Then, perhaps, justice may be done to the 

 author's views, instead of having assigned to them the mournful 

 honour of figuring somewhere in history as opinions or even 

 errors. The objects are of extreme minuteness, requiring almost 

 without exception the highest magnifying powers ; and they are 

 optically so complicated, that nowhere in the field of microscopic 

 observation is there a subject more difficult than that of muscle. 



The principal facts made known by the author in the Philo- 

 sophical Transactions of the Royal Society for 1843, bj-iefly re- 

 capitulated, were these : — The muscular fibril consists of two 

 spiral threads, so interlaced as to present a double cylinder, i. e. 

 the fibril appears as if grooved on each side, a transverse section 

 of the fibril being represented by the figure (oo ). The fibril of 

 a primitive fasciculus having transverse striae is usually so situ- 

 ated that one of its edges is directed towards the eye of the 

 observer ; whence it comes that usually thei-e is seen the spiral of 

 only one of the cylinders of the fibril. A muscle is thus nothing 

 less than a vast bundle of spirals, ap])earing short and thick in 

 contraction, long and thin in relaxation. The elliptical winds 

 of the spirals appear to have been mistaken by some observers 

 for "beads," " segments," or "particles." The dark longitudinal 

 strise of the primitive fasciculus are spaces (probably occupied by 

 a lubricating fluid) between the edges of the fibrils. The dark 

 transverse striae are rows of spaces between the winds of the 

 spiral threads constituting the fibrils. If the dark longitudinal 

 striae are sj^aces between the edges of the fibrils, the light lon- 

 gitudinal striae are the edges themselves of the fibrils; and if 

 the dark transverse striae are rows of spaces between the curves 

 of spiral threads, the light transverse striae are of course the 

 visible portions themselves of those spiral threads. The con- 

 traction of muscle does not require a flattening of " segments " 

 or " particles," as supposed by some, but simply a more trans- 

 verse direction of the spirals m their curves. Hence in contrac- 

 tion the striae of a fasciculus are narrow, and in relaxation they 

 are broad, denoting a shortening and lengthening respectively of 



