270 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



colour may be destroyed. Many worms make excellent 

 preparations, especially Nereis and coloured varieties of 

 Sabella. 



Medusae, first digested for some time in diluted alcohol 

 and then stained with carmine, make splendid prepara- 

 tions. They dry down quite thin and transparent ; but, 

 without care, are almost sure to crack and break up. As 

 they become partially dry their surface should be coated 

 with clear and colourless gum, and the slide kept under a 

 saucer with wet blotting paper, so that the gum may 

 remain liquid, and soak well into the tissues. By careful 

 management perfect and uncracked specimens may be 

 prepared and finally mounted in balsam, so as to show 

 both the general form and anatomical structure extremely 

 well. 



Probably on the whole the most satisfactory pre- 

 parations are those in which the animals are partially 

 dissected, and so arranged as to show the internal viscera, 

 as in the case of a slide of Arenicola, which shows to great 

 perfection the intestine, the digestive glands, and the 

 principal blood vessels. Partially dissected and subse- 

 quently stained Priapulus and Synapta show very well 

 the arrangement of the muscles moving the body and 

 proboscis, and also the digestive and reproductive organs. 

 When shown on the screen these last preparations look 

 more like anatomical drawings than real animals. 



The principal difficulty in making the slides is the 

 final mounting in Canada balsam, which is indispensible 

 for lantern purposes. Small bits of black cardboard 

 should be fixed at the four corners, of such a thickness 

 that the cover glass is just clear of the dried animal. 

 Before mounting, the object should be sufficiently soaked 

 in benzole, and any bubbles included in the balsam got rid 

 of by keeping the slide warm. By fixing well gummed 



