egg 0. dclicr.te larval skin v/hich envelopes all seguents and their 

 appendages so that they, with the first iaoult, enter the first 

 larval stage*. The age \7hich this, stage attains, thVt is, "the inter- 

 ' v.al of tii.ie. "which passes until the. next .or second nolt, depends to 

 a great degree up'on the tenperature. Already Dr.nncvig h;.s i/r.de ob- 

 servrtions concerning thato He found for a greater nunher '"f larvae 

 that these had ill nine days: 



V.o noulting with water of 8-10 degrees C« , 



One shedding finished with v;ater ?f 12 degrees Ce . 



Second noult begun with water -of M degrees Ge" " '" " 



Second inp.ulting finished v/ith water ^f 16 to 22 degrees Ce 

 I . ' ' ■ ■ - 



r '■ 



Appell/f observed in his research an age of five days as the 

 shortest tine for the first larval stage, mostly, however, six to 

 seveii and sonetines also eight to nine dayso For our research in 

 the Helgoland aquarium, the first larval stage vras conploted in 

 four to five days in July and August* 



Fl-oi;! the second moult, which laost still pass rather smoothly, 

 the second stage larvae then passes, distinguished from the first 

 by means of the newly appeared swinraing appendages on the ventral 

 s\Jrface of the tail (second to fifth pair of abdominal feet)c 

 ^ee illustration on page l^Oj This ptage is seven to tv/elve, 

 mostly nine to ten days old according to Appell/f; according to our 

 observations in Helgoland, on the other hand, not older than the 

 first stage, namely also only three to. five days© . 



The novj following third moult which leads -to the third stage 

 requires again a heavy sacrifice in. captivity as a rulea These are 

 not able to free either the cla\7s or the tail from the old shell and 

 perish in spite of these efforts e Appell/f s reserrch to discover 

 the basis for it, has only sho\m so much that it is necessary above 

 all things for the healtli of. the larvae to keep their containers 

 entirely fSree from collections of filth and to provide for a constai± 

 inflow' of clear .-and. ;gure water. Hovrever, indeed in spite of the use 

 of .the very greatest precautionary 'meas^ores, Appell/f. .raised from 

 1500 second stage lar'/ae, not more than 4.00 individuals in the third 

 stages The 3d stage is distinguished from the earlier stages by the 

 appearance of the sixth pair of abdominal appendages , .v.-hich takes 

 part in the formation of. the fan-shaped caudal fin© The length of 

 this stage amounts to 12.' to 14 mm a and v.-ill be, according to Appell/f s 

 data v.dth which our observations agree;, about 10 days old* , 



The now fo'llo\.'ing fourth moult which leads, to the fourth stage 

 requires again a heavy sacrafice-« There, j'vpell/f sav/ 300 individuals 

 .,. perish from 400 larvae^. The young lobsters are noxi at the end of 

 '"their plankt^-^nic life and' have a substantially changed appoarancce 

 First of all, the outer swimming appendages (exopodites) of the five 

 pairs of wal3:ing feet, whicli enable the larvae to swim about freely 

 in the. water in c particular ma.nner hitherto, ^''^ave vanished in a 



112 



