the \rrteTe Other cxn^.nals besirles fish tloubtless hunt dovm the 

 prc.cticnlly helpless., n -ticeQule larvaG. Repeatedly speoijaens 

 of PI eur ■ :b r_ci chio. £il£us rrerc throvm into the propagrtion ttinks 

 through the cction of rro.ves. Llore than once I found thr.t they 

 had swallovred Ir.r-vae, v;hich could be seen throWsh their trans- 

 parent bodies, often entirely unHgestedo Since this r.nii.TT.l 

 vj-as nuxierous in 1919 it is very t.'oII possible that many larvae 



'■' ' "■■-'^ 



current uust be a source of dan;er t- the larvae as they nre 

 transported to areas vrtiere living conditions are unfavorable to 

 theiiic Thus it is n^ winder thrt "^f the nunerous larvae but a 

 snail percentage manage to [^rcAr into c ntirlcetable lobster* Based 

 upon his studies EerricI: found that in all probability'- from every 

 30j.000i, rnd certainly frou every 10.^000 nciTly born lar- -.e not 

 nore than tt/o attained jp.arl:et size- Meek even ccncludel for the 

 Ena-lish lobster that only one in 38.,C00 reached that point, l/ 



1/ In this connection atte-ti-^n is again called to the fresh- 

 water crayfish n-hich periodically lays 100 to 250 e.cgs* Their 

 young arc hc,-.;ever, as tc develc^x.ient j to be compared with sea- 

 lobstqr in the foui-th sta;^e and, diorin^^ the first days,, continue 

 to find protection vmder the abdomen of the mother » If one nay 

 fairly cor.pare the biolo);ical values of the sea and ■ fresh-v/r.ter 

 crayfish i then abiut 200 younj; of tl-ie last named v.'-ul'.l be equal 

 to ab^ut 20,000 larvae of the first-nrned variety. 



Once the larvae cease their planlctonic inanner of living and move 

 to the bottom -f the %'.T.ter the dangers become. m\ich less. The 

 change takes place durirg the beginning of the fourth stage, 

 aftor they arc from 11 to 20 days old, depending upon circum- 

 stances. ■ , 



This change does not taJ-e place suddenly, larv ae in the 

 fourth st age irjp.y swim aroun.l often even as high as possible a lon g 

 the surface . In the rearing tanl:s too they move about continually 

 but the circumstances there cannot be comjjared with those in 

 nature especially in the absence of rll protective cover. VJhen 

 one trc.ns;jlants these young, fourth stage, lobsters fVom the tanks 

 to the aquarivjn where the bottom in covered with, stones and weeds 

 it is not long until they reach the bottom and work themselves 

 under the vreedsc After a day or two they are so well hidden that 

 it becomes a rarity to see one v;alking about in the da;y'time. 



I take this initiol s^vimming about to be in the na^are of 

 orientation, a natural instinct which can be very useful when the 

 larvae, during the transposition to the bottom stage, have landed 

 in terrain which offers unfavorable living conditions. If the 

 change were sudden and the young lobsters could not swim during a 

 considerable period at the beginning of the fourth stage, a great 

 number of them vrould succumb on bottom formations unfit for them* 



124 



