42 C. M. CHILD. 



o.oi m. is as follows: The first change is a bulging of the peri- 

 stome (Fig. 7) as in Stentor, but in these forms this does not usually 

 occur until after the cilia have ceased or almost ceased to beat. 

 This bulging is followed within a few seconds by disintegration 

 of the peristomc region including the cilia (Fig. 8), while the 

 rest of the body is still intact and then a pause of a few seconds 

 occurs. Disintegration of the body below the peristome is 

 much more rapid than in Stentor and during the next few seconds 

 the structure, except for the meganucleus, disappears completely 

 and the entoplasm swells and spreads out into the water, the 

 process beginning at the oral region and rapidly advancing 

 aborally. But the ectoplasm does not disintegrate completely: 

 a part of the body wall is elastic and as the contents of the body 

 flow out this structure contracts and remains visible for a long 

 time as a transparent skeleton or "shadow" of the body, much 

 reduced in size but retaining more or less the original shape 

 (Figs. 9 and 10). So far as can be determined the ectoplasm of 

 the peristome region does not take part in the contraction but 

 after the early stages of disintegration disappears completely. 

 Evidently the lateral body wall is differentiated in part into a 

 supporting substance which is no longer metabolically active. 

 In this connection the difference in contractility between the 

 peristome region and the lateral walls of the body in the living 

 animal is of interest. The peristome is highly contractile and 

 can be closed and opened while other parts of the body wall are 

 capable of but little contraction. The contractile region dis- 

 integrates completely at once in KCN while the non-contractile 

 region does not. 



The stalk resembles the lateral body w r all in its resistance but 

 the contractile fiber usually shows disintegrative changes at 

 about the same time as the peristome region or a little later. 

 These changes consist in a loss of the regular contour, the ap- 

 pearance of varicosities and an apparent breaking up into a 

 series of granules or droplets. Examination of the fiber with 

 very high powers has not been made. 



When lower concentrations, e. g., KCN 0.002 m. are used, the 

 death changes are limited to the appearance of hyaline or slightly 

 granular droplets on the peristome region (Fig. n) or to a bulging 



