Appendix I 



Dissection of an Amphipod 



For Right-handed Operators. 



In a flat-bottomed Syracuse dish, the amphipod is laid on its left 

 side with its legs projecting away from the operator, so that it appears 

 up-side down through the oculars of the stereoscope. The body is 

 covered to more than Uvice its depth with alcohol to prevent the 

 effects of surface tension during dissection and to ameliorate the 

 glare of reflected hght from projecting legs. 



A pair of jeweler's forceps \nth very fine points, a fine dissecting 

 needle such as an insect pin mounted on a stick of wood, and a coarse, 

 standard dissecting needle are used. At least five standard glass 

 slides, one depression sHde, and six thin cover slips are needed. A 

 small drop of glycerine is placed on two of the flat slides, a tiny drop 

 each on three of the flat shdes, and the depression-slide concavity is 

 sparingly filled with glycerine (other media are used for permanent 

 mounts; permanent slides have the disadvantage of restricting the 

 manipulation of mounted parts for 3-dimensional observation; parts 

 from glycerine sHdes may be stored permanently in alcohol in a tiny 

 vial made of a bit of capillary tubing \\dth one end closed by melting 

 in a fire, the other end stoppered ^^ith cotton, pith, or plastic foam). 



One commences removing the pereopods (legs) of the amphipod 

 at either the fourth or fifth coxa (sideplate) depending on which of 

 these coxae is largest or would pull away from the body Anthout 

 entanghng other legs or coxae. The amphipod is up-side down on its 

 left side, being held with a coarse needle in the left hand through a 

 body segment or ^nth forceps or a blunt stick, and the coxa is being 

 pulled and ripped gently at its base with the fine forceps. In most 

 cases the coxa can be pulled free of the body carrying some of its 

 proximal musculature. Occasionally the firmness of the attachment 

 dictates the use of a fine scalpel. 



When the coxa is removed, the remainder of the leg and gill (and 

 if a female the brood lamella) will come with it. As the legs are excised 

 identifying marks are noted in order to record the leg sequence for 

 positioning on the sHde. Particularly confusing are coxae 3 and 4 

 because they are often similar in size and shape, as are the last three 

 pereopods. 



507 



285-135 O - 69 - 33 



