86 C. F. MARSHALL. 



I have made gold preparations of muscle taken from the 

 "lantern of Aristotle " of Echinus, and find no trace of the 

 network of striped muscle or of any fibrillation. The cells are 

 remarkable for the clearness and transparency of their proto- 

 plasm. 



These results again agree closely with those obtained by 

 Hermann. 1 He describes the muscle of the Asterids as 

 smooth, and very seldom showing fine longitudinal fibrillation. 

 In the Holothurians he describes the muscle as non striped, 

 but states that longitudinal fibrillation is to be seen in it. 



Vermes. 



Hirudo. — The muscle-fibres of the Leech are peculiar: 

 they consist of an outer clear portion and a central granular 

 part. In gold preparations the outer part stains the more 

 deeply of the two portions of the cell and appears quite 

 homogeneous, showing no trace of a network. In osmic 

 acid preparations the outer layer appears very faintly fibril- 

 lated, but I could not identify any distinct fibrils differentiated 

 from the rest of the cell even under the -^ immersion 

 objective. 



Transverse sections of the muscle of the Leech show a 

 radiating appearance of dark and light bands in the outer 

 portion of the cell. This is, I believe, caused by the method 

 of preparation, for in some sections the outer portion of the 

 cell is broken up into pieces arranged in a radiating manner 

 and corresponding to the light portions between the radiating 

 dark lines in the better preserved specimens. I find nothing 

 corresponding to this appearance in muscle prepared by the 

 gold or osmic acid methods, which are the methods generally 

 recognised as maintaining the true histological characters of 

 cells intact. 



Wagener, 2 from transverse sections of dried specimens of 

 Leech, states that the muscle-cells consist of a central medul- 



1 ' Asteriden,' p. 94, plate iii ; ' Holothuranien,' p. 38, plate ii. 

 3 'Archiv f. Mic. Anat.,' 1869. 



