LABORATORY METHODS 217 



the volume of the catch beyond all reasonable dimensions. When specimens were sub- 

 tracted from a tow-netting a note was made on the back of the label and in the biological 

 log book. Hauls with the larger plankton nets and most of the bottom organisms 

 obtained in dredges or trawl were usually sorted on board, specimens of different groups 

 being placed in separate tubes or bottles and noted in the log book. 



In plankton work in whaling areas, where it was necessary to form some idea of the 

 contents of the nets without waiting for detailed analysis, a preliminary examination 

 was made on board as soon as an opportunity presented itself. The variety of organisms 

 in the i m. nets was generally not great, but one species or another frequently occurred 

 in prodigious numbers and it was often difficult to arrive at a fair estimate of the quantity 

 present. The procedure adopted was to find how many organisms were required to 

 displace a given amount of water and then to determine the number of the remainder 

 by a similar method of displacement. This system worked well, but the individuals of 

 a particular species taken in one haul often differed considerably in size from those 

 of the same species taken in another, so that it was usually necessary to repeat the initial 

 count for each gathering examined. With tow-nettings made with the 70 cm. and 50 cm. 

 nets the volume of plankton was measured after the larger organisms had been extracted 

 and a rough estimate made of the proportionate abundance of the different organisms 

 expressed in percentages of volume. 



In the Fixation and Preservation of Specimens no novel methods were employed, 

 but experiments were continually being made, and it will perhaps be useful to include 

 some notes on the subject. The Antarctic fauna is exceedingly rich; a successful haul 

 of the trawl entailed much heavy work and it was often difficult to find time for any 

 but the simplest technique. On one occasion, off Clarence Island, a dredge was shot 

 in 342 metres. It was only on the bottom for some five minutes, but yielded such a 

 huge mass of material that three of the staff were kept fully occupied for over twenty- 

 four hours. 



The anaesthetic most commonly used was menthol. Crystals sprinkled on the surface 

 of the water gave excellent results with many groups of animals, particularly with 

 Actinians, Alcyonaria, Hydroids, Polychaetes and Holothurians. Generally it was found 

 best to leave the bowls of animals on deck in a cool temperature, but Polychaetes react 

 very slowly under these conditions. If brought into the laboratory they were always 

 perfectly anaesthetized in about twelve hours.^ For Pteropods a few drops of i per cent 

 chloral hydrate gave splendid results and crystals of chloral hydrate often worked well 

 with Nemertines. For Nudibranchs and Tectibranchs menthol proved reasonably 

 efficient, but great difficulty was experienced in obtaining well-extended specimens of 

 Gastropods in shells. On a few occasions moderate success was obtained by menthol, 

 followed by a slow and careful addition of strong spirit to the surface of the water. 

 This, however, could only be done on the swing table and in fine weather. 



1 By this method, however, the proboscis is rarely found extruded, a condition which facilitates systematic 

 examination. 



