2OO EDMUND B. WILSON. 



pected the unequality is very much less marked than in a normal 

 specimen (Fig. I, C, D, E}. A comparison of Przibram's Figs. 

 20-23 (A. dentipes), 32-35 (A. platyrrhyncJuts] with mine shows 

 that in point of fact the difference is one of degree only ; for in 

 both those species also the figures represent the hammer-claw as 

 slightly larger. The most important addition I am able to make 

 to Przibram's result is the fact that if, after removal of the large 

 chelae, the nerve of the remaining small chela be cut at the base, 

 the reversal in some cases at least does not take place, or is 

 incomplete. 



In all, more than a hundred operations were performed, but 

 owing to the large mortality to be expected under the conditions 

 given by the lack of running water in a warm climate not more 

 than half gave definite results, and I shall here report only on 

 such cases. 1 



A first series, including a simple repetition of Przibram's work, 

 gave the following result : 



FIRST SERIES. 



A. Of 17 cases in which the large chela was removed, all 

 without exception regenerated in the reversed condition, the 

 remaining small chela being transformed into one of the large 

 type. 



B. Of i 5 cases in which both chelae were removed 14 regen- 

 erated without reversal--/, e., large and small chelae reappeared 

 on the same respective sides as before the operation while a 

 single specimen regenerated reversed. 



In three of the cases under A the larger chela (originally the 

 smaller) formed on the uninjured side was removed soon after 

 the moult, with the result that a second reversal took place, 

 restoring the original condition. One of these cases is illus- 

 trated by Fig. 3, A-C. The animal, a female, had originally the 



1 The animals were kept singly in bowls, the water being changed once or twice 

 daily, and were abundantly fed on oysters, which were greedily devoured. A com- 

 plete permanent record of the experiments was kept by preserving every cast skin and 

 the animal that emerged from it, so that there can' be no doubt as to the condition of 

 the animal before and after the moult. As a rule the animals were fixed soon after 

 the first moult ; but in cases where it occurred soon after the operation they were 

 kept until the second moult. The moults occurred at intervals of 9 to 14 days. 



