﻿186 Proceedings of the Royal Physical Society. 



In conclusion, I wish briefly to summarise the points of 

 difference and resemblance between Icthyosporidium gastero- 

 philiom as described by Caullery and Mesnil/ and the 

 Icthyosporidium here described. 



In Icthyosporidium g aster ophiliim an external envelope 

 or cyst-wall is only exceptionally present. The nuclei 

 show no rays between the karyosome and the nuclear 

 membrane. 



Plasmotomy occurs. 



The parasite is restricted to the glands of the stomach 

 and the pyloric C8eca of various shore fishes, chiefly Motella 

 mustela and Liparis vidgaris. 



In the Icthyosporidium described in the present paper, a 

 well-developed cyst-wall is very generally present. The 

 nuclei show fine rays between the karyosome and the 

 nuclear membrane. 



Plasmotomy occurs. 



The animal comes out of its cyst and breaks up into 

 reproductive bodies, which appear to be binucleate. 



The animal causes much disturbance of the tissues of 

 the host Pleuronectes flessus and proliferation of the con- 

 nective tissue. It is found in the liver, the wall of the 

 gut, including the stomach, and in the mesentery. 



The work recorded in this paper was carried out in 

 the Zoological Laboratory of the University of Glasgow 

 under the direction of Prof. J. Graham Kerr. 



Explanation of Figures. 



The figures, with the exception of Nos. 6 and 12, were drawn under 

 the 3 mm. Homog. Imm. Apochromat by Zeiss with an 8 compensating 

 ocular with the aid of the camera lucida. 



Figure 6 was drawn under a i\ oil immers. by Reichert with a com- 

 pensating ocular No. 8 (Zeiss). 



Figure 12 was drawn under the 3 mm. Homog. Imm. Apochromat by 

 Zeiss with compensating ocular No. 6. All the figures were reduced to 

 f of their size in reproduction. 



Loc. cit. 



