CONTRACTIONS IN MANTLE — LAMELLIBRANCHS 



237 



end to the other. To overcome whatever shock might follow 

 and disturb the normal behavior of the organism, the clam was 

 put in fresh water and left for six to eight hours. This clam 

 was then placed in a freshly filled jar and the oxygen consumed 

 by it in twenty-four hours again determined. Table 2 gives the 

 results of a series of such experiments. From this table it is 

 clear that the oxygen consumption of the clams in which the 

 action of the mantle has been checked is greatly reduced. This 

 fact seems to me to show that the mantle in Unio complanatus 

 is concerned with the respiratory function. 



TABLE 2 



Comparison of the quantity of oxygen consumed by specimens of Unio complanatus 

 before and after the activity of the mantle had been checked 



It may be objected, however, that the injury caused by the 

 operation may have lowered the vitality of the clam, or caused 

 such a loss of blood as to have produced death. To determine 

 whether this objection had any weight or not, clams were sub- 

 jected to numerous other operations. The distal ends of the 

 siphons were cut off, the foot was mutilated, the mantle cut 

 only on one side, or numerous small holes were made in it. 

 Clams thus operated on lived: some a week, others several 

 weeks, others even months. As table 3 shows, these operations 

 had almost no retarding effect on respiration. 



If fresh clams (Unio complanatus) are left in a sealed jar 

 containing 300 cc. of water, death occurs in not less than four 

 days. If the movements of the mantle in clams be checked as 

 described in the foregoing experiment, death occurs in twenty- 



