BY WILLIAM A. HASWELL. 
1705 
Fibres of this description have been described by Max Schultze* * * § , 
Briicke,* Yirchow,* C. F. Marshall,! and others as occurring in 
the umbrella of certain Medusae. Many of the muscular fibres of 
Holothuria, Synapta^ Echinus, Asterias and other Echinoderms 
possess, according to Leydig,! an appearance of transverse stri- 
ation which is due to their being made up of wedge-shaped segments 
closely compressed together. Schwalbe,§ however, describes the 
muscular fibres of Ophiothrix as possessing a peculiar double- 
oblique sti’iation about the nature and significance of which there 
is considerable room for doubt; it is at least probable that in this, 
as in other instances to be afterwards referred to, in which Schwalbe 
describes this form of striation, the supposed double character of the 
markings was due to a wrong deduction fi’om the appearances 
presented by the fibres. || 
In the pedicellarise of Sea-Urchins the fibres of the occlusor 
niuscle.s, as first pointed out by Geddes and Beddard,H present an 
appearance of transverse striation. These markings are not readily 
visible, at least in the Echinid I have made the subject of examina- 
tion ( Strongylocentrotus erythrogrammus ), in the living condition, 
and I have failed to bring them out by the gold method ; but in 
specimens treated with watery solution of haematoxylin and 
yellow chromate of potash, after Heidenhain’s method, they come 
* Quoted by Marshall as below. 
t “ On the structure and distribution of striped and unstriped muscle in 
the animal kingdom.” ‘Quart Journ. Micro. Sci.’ Vol. XXVIII. (1887h 
X “ Lehrbuch der Histologic.” 
§ “ Ueber den feinerer Bau der Muskelfasern wirbelloser Thiere.” 
‘Archiv fur Mikro. Anat.’ V. (1869). 
II Engelmann (“ Ueber den faserigen Bau der contractilen Substanzen mit 
besonderer Berilcksichtigung der glatteu und doppelt schriiggestreiften 
Muskelfasern.” ‘ PHuger’s Archiv,’ XXV. 1881,) recognises iSchwalbe’s 
double-obli(jue striation, and explains it much as Fol seeks to explain all 
cases of supposed transverse striation in the Mollusca. (Vide in/ra). 
IT “Sur I’histologio des pedicellaires et des muscles do I’oursiii.” ‘Comptes 
Hendus ’ 1881. Also, F. Bcddard, “ Striated muscles in Kchinida,” ‘Ann. 
Mag. Nat. Hist.’ (5) Vol. X\H1. (1886). 
