82 C. F. MARSHALL. 



striped, and showing no trace of any intracellular network, or of any 

 fibrillation. 



Hence the conclusions obtained are that in the muscular process 

 of the Hydra cell there is no form of network or fibrillation, 

 although a network is present in the body of the cell. In the 

 more highly organised Medusa the typical network of striped muscle 

 is found to be present, but in the equally highly organised Actinia 

 no network is present, nor is there any fibrillation in the muscle- 

 cells. 



These results agree with those obtained by Hamann* by the 

 method of isolating the cells by maceration in various reagents. 

 He states that the muscles of Hydroid polypes are always smooth, 

 and quite distinct from the striated muscles of the Medusa?. 

 Hamann thinks that where transverse striation has been described 

 in Hydroid polypes, it is probably due to the action of reagents. 



The Hertwigs,f in their observations on the Actiniae, describe 

 no fibrillation in the muscle-fibre. They investigated the tissues of 

 Sagartia and Anthea. 



ECHINODERMATA. 



The muscle of the Echinoderms has been described as striped by 

 several observers. Firstly, by Schwalbe; in the muscle-cells between 

 the ambulacral plates of Ojrfiiothrix, and more recently by Geddes 

 and Beddard.§ From the figure given by the latter observers it is 

 evident that the striation they describe is the false striation men- 

 tioned above as being due to annular constrictions. Schwalbe, 

 however, describes double oblique striation. 



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 clear- 

 ness and transparency of their protoplasm. 



These results again agree closely with those obtained by Hamann. || 

 He describes the muscle of the Asterids as smooth, and very seldom 



* Loc. cit., p. 20. 



t " Die Actinien." „ 



I " Archiv. fiir Mik. Anat.," 1869, p. 205. 



§ " Proc. Royal Soc. Edinburgh," 1873. 



|| " Asteriden," p. 94, plate iii.; " Holothurien," p. 38, pi. ii. 



