280 CHARLES HOWARD EDMONDSON 



mens were closed. In each of the animals the short, distal portion of 

 the style sac, separated from the remainder by the operation, was 

 filled with mud and other foreign material. 



In each of five of the specimens, on opening the long, proximal section 

 of the style sac by a dorsal, longitudinal incision, the beginning of a 

 crystalline style was evident. At this early stage the crystalline style 

 consisted of a delicate mucilaginous sheath enclosing an axillary core of 

 food and foreign material which included diatoms, sand particles, 

 spicules, etc. The dehcate style at this period occupied the entire 

 length of the sectioned style sac and was greatly convoluted and begin- 

 ning to coil (figs. 21 and 22). In three specimens the style was closely 

 applied to the right typhlosole ; in one animal it occupied the left typhlo- 

 sole, and in one it alternately lay on the right typhlosole and in the 

 groove throughout its length. 



The diameter of the crystalline style at this stage of its development 

 averaged about 0.3 mm., but varied at different levels due to the food 

 and foreign material being massed in the axis in greater amounts at 

 some points than at others. 



Apparently the digestive processes were inhibited in the clam during 

 the interval of six days, the stomach being empty and the intestinal 

 tract entirely free of food material. No change was observed in the 

 gastric shield of the wall of the stomach at the close of this period. 



Experiment 2. November 16, 1918 



Eight clams, each with the crystalline style removed by a transverse 

 -severance of the stjde sac near the distal extremity, were replanted 

 under normal conditions. The experiment extended over a period of 

 -thirteen days. 



Result, November 29, 1918. Five of the eight clams were found to 

 be alive and in good condition. The severed ends of the style sac were 

 healed in each surviving specimen, and in one or two animals were 

 'entirely closed. In each individual the short, blind end of the style sac 

 was filled with mud, while the proximal division was occupied by a 

 crystalline style in the course of development. At this period the crys- 

 talline style presented a considerable degree of advancement over one 

 -of six days' growth. It was tightly coiled throughout its length, being 

 twisted to the right when viewed from the proximal end. A food core 

 occupied the central axis of the style (fig. 23). 



Fig. 24 A sketch of the style sac opened along the posterior border showhig 

 the crystalline style of thirteen days growth lying on the right typhlosole. St, 

 stomach; Ss, style sac; Cs, crystalline style. Natural size. 



Fig. 25 The crystalline style thirty-four days after extraction. X 2. 



Fig. 26 A reformed crystalline style fifty-two days after extraction. X 2. 



Fig. 27 A crystalline style sixty-nine days after extraction. X IJ. 



Figs. 28-30 Crystalline styles approaching maturity, seventy-four days after 

 extraction. X U. Some crystalline styles were completely reformed after this 

 period of regeneration. 



