1889 - 90 .] Prof. Rutherford on Fibre of Crab and Lobster. 147 
ditions. The author is entirely opposed to the opinions expressed 
by Melland, and more recently by Gehuchten, regarding the struc- 
ture of the sarcous matter, and maintains, as he did at the Inter- 
national Medical Congress in 1881 ( Transactions International Medi- 
cal Congress, 1881, vol. i. p. 270), that the sarcous matter essentially 
consists of contractile fibrils, with an interstitial substance between 
them — an opinion previously expressed by Kolliker and others, 
and recently supported by Rollett. Fibrils are the contractile 
elements in non-striped muscle. Fluid is contained in the inter- 
stices of the invisible micellar network of their seemingly homo- 
geneous protoplasm. The shortening of the fibrils doubtless implies 
a change in the relative positions of the micellae in the networks, 
but there is no evidence of any shifting of fluid from one part of 
the fibril to another. The fibrils of striped muscle are segmented, 
and one of the events of contraction is the shifting of fluid from one 
segment to another. Each fibril consists of segments arranged in 
linear series in regular alternate order. Bowman’s element is the 
longest segment, and appears to be the only one that is really con- 
tractile. Its dimness is due to a substance resembling myeline 
enclosed in a contractile tissue. There is a node in the equator of 
Bowman’s element, the position of which is sometimes marked by 
a dim line described by Hensen, but the author finds no evidence 
of any transverse membrane there as described by some authors. 
Between the ends of Bowman’s elements there is a segment about 
half the length of Bowman’s element, termed by the author the 
intermediate segment. It is a tissue containing a watery fluid, and 
there is a globule of myeloid substance definitely located in the 
equator of the segment, and marking the position of a node; the 
author finds no evidence of a transverse membrane there, such as 
Krause and others have described. Myeloid substance also some- 
times occurs throughout the shaft of the intermediate segment, but 
always in smaller amount than in Bowman’s element. The lateral 
coaptation of the central globules in neighbouring intermediate 
segments produces the line to which attention was first particularly 
directed by Dobie in 1848. The intermediate segments appear not 
to be contractile, and probably serve as elastic buffers between the 
ends of Bowman’s elements when they approach each other during 
contraction. A third segment, termed by the author the proper 
