REGENERATION IN CAMBARUS. 303 



occurred during the night following May 6, 1907. Between 

 March 27 and May 6 no change could be detected even by use 

 of the microscope. But that changes were taking place beneath 

 the chitinous cuticle is evident from the expansion of the regen- 

 erating limb, which occurred immediately after this second 

 ecdysis (see Fig. 6). 



A third moult took place on June 19, 1907, at which time 

 the appendage again expanded, reaching the size and condition 

 shown in Fig. 7. The regenerated appendage measured at this 

 time 3.3 mm. in length ; the one on the opposite side of the 

 same somite 4.8 mm. (Fig. 8). The regeneration was equal to 

 nearly 69 per cent, of the normal size from March 24 to June 

 19, a rate which I consider by no means slow. 



Owing to an unfortunate accident this crayfish was killed on 

 the morning of July 5, 1907. Had it lived until after its fourth 

 moult it would probably have shown a much more nearly com- 

 plete regeneration of the appendage. 



No. 7. C. (Bartonius) bartoni, ?. Fourth left pleiopod 

 removed March 24. The first moult after the operation took 

 place the night of April 22, 1907. The amount of regeneration 

 while not extensive was plainly visible. The second moult 

 occurred May 25, 1907. The regenerating appendage expanded 

 to nearly half the natural size, immediately after the exoskeleton 

 was cast (Fig. 9). 



No. 3. The same as No. 7 except that the fourth pleiopod 

 was removed from the right side instead of the left. The first 

 moult, on March 30, showed a small whitish papilla a little over 

 one mm. in length, projecting from the base of the amputated 

 limb. This projection increased slightly with age, but this indi- 

 vidual was killed in July by the water in the vessel receiving 

 direct sun-light through a partially open window blind, thus 

 becoming much overheated. Fig. 10 reveals internal develop- 

 ment. A later moult would probably have given results similar 

 to No. 7. This specimen was probably a year, or perhaps even 

 two years, older than No. 7, and consequently only one moult 

 was recorded between March 24 and July 5, while some of the 

 smaller, younger specimens moulted three times in a shorter 

 period (cf. No. 4). 



