NATURE STUDY IN SCHOOLS. 



127 



It must have food as well as oxygen. If we look carefully, we shall 

 find near the end opposite the siphon, three or four slender projections. 

 These surround an opening. This opening is the mouth. The food of the 

 clam consists of particles of animal and vegetable matter found in the water 

 which comes in through the siphon. The small projections surrounding the mouth 

 help to draw in the food particles. The food passes into the stomach and 

 intestine, the soft portion of the clam's body. The material which is not di- 

 gested is carried out through the small siphon. There are tiny blood-vessels 

 in the different parts of the body. The blood is not red like ours, but 

 colorless, much like water. It is sent along by the beating of a small heart. 

 Nourishment is absorbed from the stomach and intestines, and is carried by 

 the blood to other parts of the body. 



Near the mouth of the clam you will find its one foot. This seems a 

 queer place for a foot, does it not ? It can be thrust out through an open- 

 ing in the mantle. The clam does not need to move about much, but by 

 means of this foot it can have a little motion. Because the foot can be thrust 

 out and drawn in, we know that the clam must have muscles. You remem- 

 ber that we found that the shells are held together by muscles. 



The clam is very sensitive to touch. If the siphon be touched, it will 

 at once be drawn into the shell. If the shells are partly open and we touch 

 them, they will be drawn tightly together, probably for greater protection. 

 Clams are found along the shores of bodies of salt water. As the tide comes 

 in, fresh sea-water is brought across the mud. Thus the clam, having its 

 siphon projecting upward, gets fresh oxygen and fresh food. The clam is 

 certainly a very interesting animal. At first it does not seem that there can 

 be so much active work going on within such a small body. In the study of 

 the clam, we see that the smaller animals have been as carefully and thoughtfully 

 provided for as the larger ones. 



Figure 67 



Sead of Red Cross Bill, 



