APPENDIX. 415 



99). Examine the soft parts in a dish of water or of fifty per 

 cent, alcohol. Note the mantle lobes, the gills, the foot, the 

 mouth parts, etc. Cut open the hody, and trace the digestive, 

 nervous (Fig. 134), and the principal parts of the circulatory 

 systems (Fig. 46). Harden specimens in alcohol, and make 

 transverse sections through the body, and examine the sections 

 again in dishes of fifty per cent, alcohol, tracing in this way 

 , the course taken by the digestive system (Fig. 78). 



Arthropoda. — [A) Crustacea. — Use the Lobster or Crayfish. 

 Study living specimens in jars of water. Examine the manner of 

 walking and swimming ; of grasping food and chewing it ; of 

 defending themselves ; the motions of the antennary organs, the 

 eyes, and the appendages of the abdomen. Note the segmented 

 structure, the segments being grouped into well-defined regions 

 forming the cephalo-thorax and the abdomen. Note the presence 

 of a pair of appendages on each of the abdominal segments ; 

 the similarity of structure of all these appendages except the 

 last, and the extreme specialization of this one. On the cephalo- 

 thorax look for segments ; note here also the arrangement of the 

 appendages ; remove them in order from one side, and trace the 

 modification of the same fundamental plan of structure. Open 

 one of the large claws and study the contained muscles. Note 

 especially the arrangement and structure of the mouth parts, 

 eyes, and antennary organs (Fig. 250). With a pair of strong 

 shears cut through the " shell " along each side and remove the 

 roof of the abdomen, thus exposing the muscles within, and the 

 posterior part of the circulatory and digestive system. Note 

 the arrangement of the muscles and blood-vessels. In the same 

 manner remove the top of the cephalo-thorax, examining the 

 chamber in which the gills lie and their arrangement. The 

 heart and stomach will now be ejjposed, also the "brain " (Fig. 

 70). Examine all these. Kemove the digestive system, and, 

 lying below it, find the ventral nerve chain. Look also for 

 nerves running to the eyes. 



(i}) Insecta. — The large Locust or Grasshopper will be use- 

 ■iul to study the general characteristics of insects. It is diflScult 

 to keep living specimens confined for any great length of time, 

 consequently the best observations of their habits must be made 

 out-of-doors. Recently caught or alcoholic specimens may be 

 used for studying the anatomy. Notice here, as in the Lobster 

 and the Earthworm, that the body is segmented ; but the seg- 



