344 NATURAL HISTOEY OF OUR SHORES 



These are the conditions necessary (given fair temperature, 

 say about sixty degrees Fahr.). As the young lobsters 

 hatch and gain sufficient strength (usually ten or twelve 

 hours after hatching) they will swim over the top of the 

 jar into the larger vessel, whence they can be fished out 

 and examined from time to time. The same plan can be 

 employed to advantage with eggs of any other marine 

 animal. 



There will be a heavy mortality, but this must not dis- 

 courage the student. The same takes place, perhaps to 

 quite as great an extent, in nature, and he will find abundant 

 material for observation and study. 



Another plan, and one by means of which I have reared, 

 or I had better say "raised," many unusual larval forms, 

 is by means of a series of dishes arranged on a gradient, 

 so that the flow from the reserve tank passed from one dish 

 to the other through glass tubes let through their ends, 

 the overflow of one dish supplying the next, and the final 

 overflow, into a large pan, being once a day transferred to 

 the upper tank. 



The inner ends of the glass tubes that carried overflow 

 were covered with muslin, to prevent the young animals 

 from being carried out. 



The larval stages of nearly all marine animals crabs, 

 prawns, fishes, molluscs, etc. and the alternate or medusid 

 generation of the zoophytes, can be studied in this way, 

 and interesting and instructive recreation be thus obtained. 



And now my task is done. I had promised "an 

 outline," and I have given one a very bare one, I am 

 aware. Still, I have pointed out the chief lines of a 

 pursuit which has yielded me pleasure for many years, 

 and this pleasure is enhanced by the thought that 

 perhaps by means of this little book I may be able 

 to pass it on. 



