SEA-FISHERIES LABORATORY. 295 



ttient the alimentary canal will contain very little sand. 

 This can usually be ascertained by examining the worms 

 by strong transmitted light, when any sand present in the 

 gut will.be detected. As soon as all the sand has been 

 voided the worms may be placed in a dish containing a 

 smaller quantity of sea water. They may then be 

 narcotised by dropping absolute alcohol little by little on 

 to the sea water until the liquid contains about 5 per cent, 

 of alcohol. After a few hours the worms will be sufficiently 

 narcotised and may then be killed in an extended 

 condition. Before attempting to kill them ascertain by 

 touching them if they are thoroughly narcotised. Care 

 should be taken not to allow the worms to become quite 

 dead in the alcoholised sea water, as the tissues suffer. 



A good killing and fixing mixture is sublimate acetic 

 (95 parts saturated sublimate solution and 5 parts glacial 

 acetic acid). As soon as the worms are dead transverse 

 incisions* should be made in the body wall at intervals of 

 i to | inch, so as to allow the re-agents to penetrate 

 rapidly and fix all the internal organs. If the operations 

 above described be carefully carried out the worms will 

 be killed straight, a great convenience when sectioning. 



After a few hours in sublimate acetic the worms are 

 washed in running (fresh) water for a few minutes, and 

 then transferred to 50 per cent, alcohol (two or three 

 hours), to 70 per cent, and to 90 per cent, alcohol (two or 

 three changes). To the latter a few drops of tincture of 

 iodine should be added to dissolve from the tissues of the 

 worm the last traces of sublimate. Fresh iodine should 

 be added as the liquid becomes decolourised, and this 



* This should be done as rapidly as possible, as on contact with 

 metal a deposit of mercury is liable to be formed in the tissues. The 

 worms should be transferred from one vessel to another (where that is 

 necessary) by means of glass, horn, or paper lifters, and all contact 

 with metal avoided. 



