LIFE-HISTORY OF BUCEPHALUS HAIMEANUS. 671 
beds in Newport River on which I knew that about 25 per 
cent. of the oysters were infected, and, after marking them, 
placed them in wire cages with oysters from Fort Macon, 
where | had never found the parasite. The cages were then 
sunken in the water beneath the wharf at the laboratory. 
The cages used for this purpose were made of galvanised 
wire netting, and were about two feet square and six inches 
deep. 
In cage No. 1 were placed twenty-four Newport River 
oysters and eighteen Fort Macon oysters. 
In cage No. 2 were placed twenty Newport River oysters 
and twenty Fort Macon oysters. 
Cage No. 1 remained in the water until November 1st 
(about six weeks) when it was taken up and its contents sent 
to me at Baltimore. Four of the Newport and three of the 
Fort Macon oysters had died during the experiment. Exa- 
mination showed that of the twenty Newport oysters remain- 
ing, five were badly infected. None of the Fort Macon 
oysters showed any signs of infection. 
Cage No. 2 was sent to me on February 1st. In this cage 
two Newport and two Fort Macon oysters had died during 
the experiment. Of the eighteen Newport oysters, four were 
infected, while none of the Fort Macon oysters showed any 
trace of infection. 
In June, 1903, I began a modification of this experiment. 
From a large number of infected oysters I selected specimens 
in which there was a great abundance of sporocysts, and 
consequently a great number of embryos in all stages of 
development. These oysters were torn to pieces in a dish of 
sea water and a considerable quantity of cercariz and sporo- 
cysts thus obtained. By slightly separating the valves of 
the shell of uninfected (Fort Macon) oysters with a knife, 
the tip of a pipette containing cercariz and sporocysts could 
be inserted, its contents ejected into the mantle cavity of the 
oysters, and the valves then allowed to close. 
Thirty of these oysters were immediately placed in a cage 
