\7hich men.ns three to f'oiir dciys older thnn the r.vera^i^e nge of this 

 stage. The experiment vras terninnted on the sniiie dny ovdng to 

 the large mortal ityo 



It is a pity that not as riony tcnporature neasureinents v:ere 

 .made as I would noiT rrish, the measurements rade showed hovrever a 

 pronounced tcT:iperat\U'e difx"ercnce between s ui'face and depth, since 

 in a depth of 10 iicters it was 1 to 2-g-^ C, colder than on the 

 surface. That tlie delayed moulting and also vrith it the slor/er 

 grovjth mainly is to b e attributed to a lower temperature and not 

 for example to unsuitable light conditions is evident in that the 

 rearing experiments on the larvae Vv'liich I undertook under the 

 influence of the various colored lights (by covering the boxes vath 

 red;, blue or green glass) as vrcll as in complete darkness showed that 

 no definite unfavorable influence from thic on the gro^rth v/as to be 

 proved* l/ Rejriarkable also was the gruot mortality in the larvae 



1/ Hadley believes even to have found for the /aierican species 

 that larvae in boxes in which the light had been dinned by a 

 cover develop slightly quicker than in other boxes (l.Ce204-) 



Virhich vrere held at a depth of 10 metres, however I do not dare to 

 consider this v/ith certainty as the direct cause of the lovrer temper- 

 ature since also other circumstances could have contributed to it« 



Be it as it may, the fact that the prervailing lovrer temperature 

 in the somev/hat deeper water layers influences unfavorably the 

 development of the lobster larvae indicates therefore with certainty 

 that the natural habitat of the lobster lr,.rvac is the upper water 

 layt^rs with the highest tejnperature. The dimensions of these water 

 layers may indeed differ according to the various years and the 

 various coastal areas. Hylrographicrl investigations show thr^t 

 often during the si.w:aaer in a depth of 10-20 metres a distinct bound- 

 ary occurs for the tem-peratvire as well as the salinity I'/hen the 

 temperature in the depths sinks suddenly and the salinity increases 

 and. v/e can consider it as probable that lobster larvae which, forced 

 by unsuitable circuiratances to remain in these depths for a longer 

 time must eventually die. And that the unusually loir temperature 

 at the surface in many years can contribute to a .lovrering of the 

 lobster larvae stock is probable. ■ • - 



As already evident from the foregoing str.tements it v:ould 

 hovrever be wrong if one would look for the reason of the difference 

 of groirth, which the individuals show, only in the influence of the 

 external environment. All rearing experiinents shavr on the contrary 

 that although all individuals of the same age live cro\Tded together 

 in a relatively small box together where there ca.n be no question 

 of a difference of physical conditions, yet the moulting for one 

 individual ma.y take place at a different time than for the other 

 just as one individual grov/s more 'than the ether. In other -words 



