HABITS AND DEVELOPMENT OF THE LOBSTER. 85 



product of each pair, the original number of lobsters would be doubled. If a similar 

 increase were to take place in the human species famine and starvation would undoubt- 

 edly follow in many places, but so far as abundance of food is concerned it is certain 

 that the lobsters could maintain themselves in far greater numbers than at present. 



Reproduction is an expensive process, and the birth-rate among animals is there- 

 fore kept down to a minimum, which will provide against extinction by discriminate 

 and indiscriminate causes. A high birth-rate is bad for the individual, but is good 

 for the race, and is only resorted to when the chance of survival becomes very small. 

 When the parents foster and protect the young, as is the case with birds and mam- 

 mals, a very low birth-rate will suffice to maintain the species, but when these condi- 

 tions are not present and the chances of reaching maturity are less and less assured, 

 the birth-rate has in many animals been more and more increased, until in extreme cases 

 the number of eggs produced amounts to tens or hundreds of millions. 



The number of eggs or young produced by an animal is thus directly related to 

 the habits of the animal in its early and adult stages. This is well shown within the 

 group of the Crustacea by a comparison of the common edible blue crab (Callinectes 

 hastatus), or the lobster, with a deep-sea shrimp (Parapasiphae sulcatifrons). The 

 shrimp lays from 15 to 19 eggs, each one of which, according to Prof. S. I. Smith, 

 measures 4*2 mm. (about one-sixth of an inch) in diameter, and is "approximately 

 equal to a hundredth of the bulk of the animal producing it — a case in which the egg 

 is relatively nearly as large as in many birds." The blue crab is said to lay 4,500,000 

 eggs, each of which measures only 0-28 mm. in diameter. We must infer that this 

 shrimp has a short larval period ; probably it hatches from the egg with all the external 

 characters and habits of the adults. The blue crabs, on the other hand, or the young 

 lobsters, leave the egg as immature forms, or larvae, and have a number of weeks 

 of free-swimming life, during which time they are subject to innumerable chances of 

 destruction. 



In the tapeworm we have an example of an animal which produces an extraor- 

 dinary number of eggs, possibly reaching to tens or hundreds of millions. In some 

 species the body is composed of as many as 3,000 segments, each of which is really 

 an hermaphrodite individual which produces thousands of eggs. In order that any 

 of this vast progeny may come to maturity, the eggs or embryos must be eaten by 

 an herbivorous or carnivorous animal, and the flesh of this animal containing the 

 encysted parasite must be eaten by still a second animal of a particular species, which 

 forms the second host. It is thus evident that if the number of these eggs were few 

 there would probably be no survival at all. 



The production of a large number of embryos invariably means destruction to all 

 but a very few, and if, in our attempts at artificial propagation, we place the young on 

 the same footing which they would acquire in the ordinary course of nature, we can 

 not expect that nature will treat them with any partiality. 



The hatching aud immediate liberation of the young of the lobster can be easily 

 accomplished by the methods now in use, but it is clear that in order to sensibly 

 affect the total supply, such a method must be conducted upon a very large scale. 

 Allowing the survival of 2 individuals out of every 10,000 hatched, we would have to 

 hatch 1,000,000 eggs to produce 200 adults, and 1,000,000,000 to produce 200,000. Since 

 hundreds of thousands of lobsters are captured every month during the best part of 



