SEA-FISHERIES LABORATORY. 129 



pressed, it liberated immense numbers of spores, which 

 were in great part aggregated into globular or oblong 

 clusters, the larger being as much as '02 mm. (20/*) in 

 diameter. The spores themselves were short and thick, 

 with bluntly-rounded ends, their length being about 

 "0025 mm. (2J/i), and a little less in breadth. Here also 

 there is little doubt that we have to deal with a Crypto- 

 cyst (Microsporidian), but in the absence of figures it is 

 rather uncertain in what genus this parasite should be 

 placed. From the mention of distinct clusters or clumps 

 of spores, and the shape of these latter, I am somewhat 

 inclined to regard this case as one of infection by 

 Pleistophora, rather than by Glugea — the reason will be 

 referred to below. 



My own acquaintance with these parasites began in 

 the summer of 1901, when Mr. Todd, then Assistant to the 

 Director of the Plymouth Marine Biological Laboratory, 

 brought to my notice the intestine of a plaice which, 

 although, unlike Johnstone's specimen, it was quite 

 healthy in appearance, presented certain abnormal 

 features. 



The gut had been fixed in Corrosive and Acetic, and 

 preserved in spirit, and shewed at intervals little oval 

 patches, usually projecting slightly ^ on the outer ccelomic 

 side. Besides these, there were little out-growths of the 

 tissue of the wall, often in the form of pear-shaped appen- 

 dages, attached by the narrow end to the gut. These 

 patches and projections indicated the site of the infection, 

 and were readily to be distinguished by their rather 

 different colour, having a faint reddish tinge added to 

 the pale nondescript shade of the preserved gut. I 

 gathered from Mr. Todd that, when fresh, the spots were 

 of the usual Sporozoan opaque-white. A point worth 

 noting in the position of the parasites is that they were 

 K 



