

SEA-FISHEEIES LABORATORY. 161 



II. Observations upon oysters subjected to various 

 abnormal conditions in the laboratory.* 



(a) A series of oysters placed in sea water and allowed 

 to stagnate, in order to determine the effect of non- 

 aeration. 



(6) Similar series in water kept periodically aerated. 



(c) A series placed in sea water to which a quantity of 

 fresh (tap) water was added daily, to determine effect of 

 reduction of salinity. 



id) A series of oysters weighed approximately, and fed 

 upon the following substances, viz. : — (1) Oatmeal, (2) 

 Flour, (3) Sugar, (4) Broth, (5) Living Protophyta (Dia- 

 toms, Desmids, Algae), (6) Living Protozoa (Infusoria, 

 etc.), (7) Earth. 



In this series of experiments the oysters were fed every 

 morning and the water aerated, but not changed (evapor- 

 ation was compensated for by the addition of a little tap 

 water as required). The oysters were weighed from time 

 to time, and observations made upon the apparently 

 harmful or beneficial effects of the above methods of 

 treatment. 



(e) A series of oysters placed in sea water to which was 

 added daily — 



(1) Healthy faecal matter. 



(2) Typhoid faecal matter. 



(3) Pure cultivations of the typhoid bacillus. 



The oysters were carefully examined to determine their 

 condition, with special reference to condition of branchia, 

 alimentary canal, adductor muscle, and viscera generally. 

 The contents of the rectum, as well as the water in the 

 pallial cavity, were subjected to bacteriological analysis 



*The oysters were kept in basins in cool rooms of constant temperature, 

 shaded from the sun, both at the Port Erin Biological Station and also in 

 the Pathological and Zoological Laboratories at University College, Liverpool* 



