269 



On the preparation of MARINE ANIMALS as 



LANTERN SLIDES to show the FORM 



and ANATOMY. 



By Dr. H. C. Sorby, F.R.S. 



[Read April 10th, 1891.] 



The author exhibited 30 lantern-slide preparations of 

 marine animals, including representatives of most of the 

 leading groups. Flat fishes, like soles or dabs, about 1^ 

 inch long, when mounted in Canada balsam are sufficiently 

 transparent to show their general form and anatomy very 

 well. Crustaceans which are not too thick may be digested 

 in diluted alcohol, to which a little hydrochloric acid has 

 been added, to remove the carbonate of lime. Their form 

 then remains perfect, though they become so pliable as to 

 make it easy to gum them flat on the glass. Those, like 

 Caprella, which become too transparent when mounted in 

 balsam, may be previously stained with carmine. 



Success in the case of soft bodied animals, like Ascidians, 

 Nudibranchs, Annelids and Medusae, depends to a great 

 extent on the fact that, when properly arranged out, they 

 dry first round their edges, and adhere to the glass in such 

 a manner that on subsequent complete drying contraction 

 takes place almost entirely in a direction perpendicular to 

 the plane of the glass, so that they become quite flat and 

 thin, without material change in the original outline. 

 Those which, like Medusae, contain so much salt water 

 must be digested for some time in diluted alcohol, but 

 some Nudibranchs and worms must be kept in the alcohol 

 no longer than is absolutely necessary, or the natural 



