in the open is nissinj;; entirely* Directly after the larvae are 

 born, they seek the surface of the water and begin their planlc- 

 tonic life. In a dark fish tanlc it is very easy to attract 

 toj^ether all the larvae to a siiir^.H place throUij;h a sin,;jle falling 

 li^ht ray» ToT/ards the end of the second and third sta;_;es this 

 positive pliototaxis is much less present, or it is even ne[;ative» 

 One can often observe that the larvae seek the shade. Hadley has 

 described very fully for the Ai.ieric an lobster the influence of 

 light stimuli on the behavior of the larvae. 



Yet tov/ards the current direction the larvae are very sensi- 

 tive; they face the head to it when the current is not much too 

 strong. 



The larvae lack an organ of equilibrium or in any case it is 

 only imperfectly developed. They orient theiiiselves in space by 

 - the light and the eyes: they turn the bach to the place r/hich has 

 I!.' tji-e most light, normally the sky. Let one hovrever allov/ a light 

 to fall into a pool only from beneath, then one sees that the 

 larvae, almost without exception, turn themselves imraediately and 

 swim quietly farther with the abdomen to\7ards the top until the 

 light ap;ain falls normally xrom above. Tiie clav/'s occasionally 

 become stretched upwards, a proof that they hang dovm not passive 

 and loose in spite of the swimming animal, but become actively 

 stretched dowm';ardly. The young lobsters of the fourth stage 



react equally quickly as the' larvae. 



I. ~ 



Although the lobster larvae are planktonic organisms, which 

 ■must OQCur very r^enerally in many places, yet they are caught only 

 seldom with surface nets; most frequently of the Idrvuc first titd 

 fourth stage were still caught. The larvae, in nature very prob- 

 . ably keep themselves often in the dee■^er vrater layers. Much about 

 their life history lies still in darlcness. So it is inexplicable 

 that in distinct small districts (Helgo'land, Osterschelde) not 

 all the. lobster larvae d.uring the tv/o or three v/eeks of their 

 larvf.l life are carried on far from the dv/elling place of their 

 .' parents by the ebbing and flowing' currents whose resultant can 

 :i. yet never be exactly zero. One has perhaps thought that the egg- 

 ?v bearing feiiiales, travel (off) against this current;- resultant, in 

 .order to compensate the spread of the larvae in a down-current 

 direction (Meek 107); such upward migrations however do not occur 

 generally. 



YJhen the young' lobsters have reached the fourth stage, they 

 immediately seek the bottom of the sea. Generally, ho\rever not 

 at once, indeed they ascend even more frequently from the bottom 

 and swim again on the surface for some time. Fast rules are not 

 ■to be given 'and great individual differences occurs The transit- 

 ion f r..om 'a planlctonic to a bottom aiiimr.l is therefore a slo\7 one, 

 which is of Very great importance for the discovery of a suitable 

 dv/elli-ng place. If they have settled dovm on a mud bottom, v.'hich 

 is not suitable for them, they can entrust themselves ancT 



144 



