MARINE BIOLOGICAL STATION AT PORT ERIN. 43 



in the productivity of the plaice fisheries several years after- 

 wards. If (as is very likely) these favourable conditions are 

 repeated for several years the effect (as regards the fisheries) 

 will be still greater. This is, of course, Dr. Johan Hjort's 

 well-known hypothesis. 



The Edward Forbes Exhibition.* 



The Exhibitioner for the year 192 1 was Miss Maisie Hobbins, 

 B.Sc, who spent a month at Port Erin (21st March to 16th 

 April) working on the life history of the Sporozoan Merocystis 

 kathae. This organism is parasitic in the renal organ of the 

 common whelk (Buccinum undatum). A large number of 

 whelks from Port Erin, Pie! and Millport have now been 

 examined and, so far, very few have been found to be uninfected 

 with Merocystis. It has been supposed that the parasite 

 passes through a sporogenous stage in the renal organ of the 

 whelk and so the main object of Miss Hobbin's research was 

 to discover a second host. Two series of experiments were 

 therefore made. (1) The infected renal organs of the whelks 

 were dissected out and offered as food to various crabs 

 (Eupagurus, Portunvs and Carcinus). The latter animals were 

 kept in separate tanks. Several died and the alimentary 

 canals were removed, preserved in Bouin's Fluid and taken 

 back to Liverpool ; (2) Pieces of the infected renal organ of 

 the whelk were enclosed in the mantle cavities of the boiled 

 mussels used for feeding the fish in the Aquarium. These were 

 offered to various cod in one of the tanks and were readily 

 eaten. During the fourth week of the experiment one of the 

 cod died. Its alimentary canal was dissected out, fixed in 

 Bouin's fluid, and taken back to Liverpool. The object of these 

 experiments was to find whether or not Merocystis passes 

 through a schizogenous phase in the tissues of a second host. 

 The latter has to be discovered by various " feeding experi- 



* For the Regulations with regard bo bhe Exhibition, see pp. 57-58. 



