PROCESS OF REGENERATION 105 



Wherever susceptibilities are compared, I have always done so 

 at the same time, and with the same cyanide solution, thus 

 avoiding sources of error arising from differences in the solution, 

 external conditions, etc. I have found it most convenient to 

 carry out the experiments in watch glasses. The animals are 

 placed in these, freed as much as possible from water, and a 

 cover put on in such a way as to exclude all air bubbles. In 

 such covered watch glasses evaporation of the cyanide is reduced 

 to a minimum, and the whole can be placed under the low power 

 of the compound microscope, and the progress of the disinte- 

 gration followed very exactly. 



The following changes take place in cyanide. The worms at 

 first move about vigorously but eventually pass into a state of 

 anaesthesia. The peristalsis of the intestine and especially of 

 the dorsal blood vessel keeps up as a rule until the time of death. 

 Frequently there is a swelling of the animal, due to the intake of 

 fluid into the coelomic spaces, so that the body wall is distended, 

 except at the septa, and the animal then resembles a string of 

 beads. This condition appears to be a regular ante-mortem 

 change since it also occurs in pieces dying in water. The death 

 point is characterized by an abrupt change from the normal 

 yellowish-red color of the oligochaetes to an opaque white; this 

 change of color is quite apparent to the naked eye, and under the 

 microscope can be followed from segment to segment. Simul- 

 taneously with or immediately following this alteration of color, 

 the body wall breaks (it may previously have shown blister-like 

 elevations), and all the structures disintegrate into a shapeless 

 mass of granules. This disintegration, as already indicated, 

 does not occur simultaneously throughout the animal, but pro- 

 ceeds in a perfectly definite manner along the antero-posterior 

 axis. This disintegration gradient of the various oligochaetes 

 will now be described in detail. 



2. The primary gradient 



The kind of gradient which Child has described for Protozoa, 

 Coelenterates andflatworms (Child, '13 c, '14 a, '14 b) constitutes 

 what I call here the primary gradient. In these forms, disinte- 



