Self-evisceration in the Aster oidea. 283 



wliile a sixth mass of coeca issued from tlie wart-like pro- 

 tuberance halfway down the upper surface of the super- 

 numerary sixth ray. Each of the five normal rays was 

 ruptured for a leng-th of 5 mm. on the upper surface close to 

 the tip, and from these small slits protruded the whole csec.il 

 contents of the ray still paired by their basal conneclion. The 

 animal thus eviscerated was in a lively condition. It moved 

 across the dish with its tube feet in active motion and the 

 dermal branchiae exserted, and when turned over on its back 

 was able to quickly resume its normal position. The rays 

 had become flattened and in places even concave by the 

 withdrawal of the c?eca. This individual lived for three days 

 after the rejection of its cfBca, and on the 22nd April, the day 

 after this rejection, a mass of orange gonads was seen to 

 issue from the ruptured tip of one of the arms. Though 

 changed from time to time, the water in which this specimen 

 was kept became rather stale at intervals, as it did with the 

 other specimens dealt with in these notes. 



The actual process of self-evisceration, which I had no 

 opportunity of observing in this six-rayed individual, I was 

 enabled to watch closely in the larger and normally five-rayed 

 specimen taken on the same day, tlie 17th Aprih At 11 KM. 

 on the 23rd April the first sign of extrusion was noticed. 

 A small lump of tawny cseca made its appearance on the 

 upper surface and near the tip of one of tlie arms. Three- 

 quarters of an hour later this extrusion was completely 

 withdrawn and no trace of rupture could be made out on 

 examining the tip of the arm witii a hand lens. No further 

 extrusion took place that day, but at 8 A.M. on the following 

 day, 24:th April, a mass of caeca as large as a pea was 

 observed at the extremity of one ray and a much smaller 

 mass at the tip of a second and adjacent ray. Half an hour 

 later the smaller mass wns found to have doubled in size and 

 at 10 A.M. a fairly large extrusion appeared at the end of a 

 third ray, adjacent to those already luptured. Nearly two 

 liours later, at 11.45 A.M., measurements were taken of the 

 caeca extruded from the three couiiguous rays, when the 

 lengths were found to be 4, 8, and 11 millimetres respectively. 

 About this time swellings and pale bands and blotches were 

 seen to travel very slowly along the ruptured arms and to 

 come and go on different parts of the disk, suggestive of the 

 slowly propagated swellings which precede self-evisceration 

 in certain Holothurians. 



Further measurements of the extruded caeca made at 

 12,45 P.M. the same day gave lengths of 4, 10, and 16 

 millimetres, and about the same time orango-colonred gonads 



20* 



