I/O MAX MORSE. 



The process of disintegration of the cells of the hydranth 

 which has been cut off from the stem, is ushered in by dissocia- 

 tion of the cells of the entoderm (Fig. 2). There is no con- 

 stancy in location of the origin of this process, but, in the main, 

 it seems to set in at the proximal end, i. c., at the end formerly 

 connected with the stem. The entoderm cells leave their posi- 

 tions around the periphery of the hydranth, immediately beneath 

 the ectoderm and come to fill the whole of the cavity of the 

 hydranth. This cavity, at the same time, begins to become 

 smaller in volume. Then, after a time, the ectoderm cells begin 

 to participate in the process of dissolution. The gonanths are 



FIG. 2. Hydranth which has begun to disintegrate, in sagittal section. A 

 gonanth is shown also in section ; the cells are normal. 



the last to suffer (see Fig. 2). Even after the hydranth has 

 begun to lose its shape, as it lies at the bottom of the dish, these 

 reproductive bodies show little histolysis. 



In order to determine what factors \vere operative in causing 

 autotomy, the writer performed a series of experiments on 

 Tubularia. The following external factors were considered: 

 (i) Temperature effects (a) heat, (b) cold; (2) light, involv- 

 ing its absence, darkness; (3) gravity; (4) aeration; (5) me- 

 chanical factors, such as abrasion, force of current, etc. 



i. Temperature. (a) Effects of Heat. A fingerbowl, con- 

 taining a dozen stems of Tubularia fresh from the sea, was 

 placed in the direct sunlight, where the temperature registered 



