REYER.-AL OF ASYMMETRY IN CRUSTACEA. 245 



.iii'l tint- by a -uri <it compensatory regulation the animal'- asym- 

 metrical ondition i- quickly reestablished. 



\Vil-on repeated Przibram's experiment- on Alphcns Itctcro- 

 chflis with -imilar results, hut carried tin- experiment- further, 

 hoping to analyze the factors concerned in the reversal pro., --. 

 After removing the great chela the nerve trunk leading to the 

 -in. ill i lii-la <t the opposite side was Hipped in order io u-t 

 \\hetln-r tin-re- was a nervous control determining the growth of 

 i In- -mall chela into a large one. After Mich an operation the 

 -mall chda wa- generally thrown off and only \\\ -] -inn n- are 

 -,iid io I -I- l"-\ ond (|uestion, >'et "one of the-e did in it moult quite 

 noniialK and the other not at all.". The evident e, ihen. doc- not 

 warrant conclusions as to the CailSC of reversal of ,i-\mmeir\ ill 

 i he cln-I.e. Wilson finally helievcs that the initial factor that sets 

 iii moiiiui the complex process of different iat imi of \\hich either 

 -id< 'lahle, is primarily only ;i dilh n me in the amount of 



material < m the two sides. "Removal ot t he lari^i chela < <\ >\ i< .u-l\ 

 d the asymmetry in respect to the amount of material and 

 nm-t. l-mporaril\', at least. K-ad to a functional IUT\OU- dillci- 

 eip Such a suggestion may easily he submitted to ( \pi ri- 



mrntal test, for example, after removal of the l.ir^c hcl.i fr..m 

 one -ide of the body if several posterior appendage- be ivmo\ed 

 lioni the other side the greater amount of material may -till 

 remain on the original large chela side. I u. I, .1, illust rate- 

 tin- operation. I'nder the-e conditions \\ill a large chela re- 

 generate I nun the -tump ot tin old one, in-tead of ari-in^ I 

 gii\\ th o| the -mall In -t chela of the oppo-ile -ide.' 



X^ain, tin- propn-iiion ma>- he tested b\ removing hoth the 



a and -mall chela- o| t he lir-t pair and in addition amputating 



several legs "ii the -ide of iln- large chela; the operation i- illu-- 



tratedb\ Fig. i, J fh( greater amount of material is no\N on 



the original -mall chela -ide; \\ill thi- extra amoiini caU5( 



it chela to regenerate from the small stump instead of from the 



-tump of the great chela which i> on the -ide \\ith le material' 

 Lastly, \\hen onl\ a |iortion of the great chela i- amputated 

 doe- it regenerate in the original condition Of become a Miiall 

 chela, while a large chela appear- on the opposite -ide through 

 a metamorphosis o| the -mall tir-t chela.' 



