National Geographic : 1916 Jun
A HARD-SHELL CRAB CONVERTING ITSELF INTO A SOFT-SHELL The difference between a hard-shell and soft-shell crab is simply one of time. Every now and then the crab needs to grow a little, so its body gets soft and its hard shell splits open. It is then enabled to pull itself out of that shell and to grow while a new one is in the process of forming. When this process is completed, it ceases to be a soft-shell crab and once more joins the ranks of the hard-shells. This change takes place several times a season. uance unless some practical outcome is shown or reasonably sure of accomplish ment. Fortunately, the Bureau of Fisheries has from the outset been recognized as an institution whose scientific investiga tions and experiments lead to important practical ends, and the liberal appropria tions for this purpose made by Congress year after year are an evidence of the way in which the lawmakers regard this service. Our artificial propagation of food fishes, which is the most extensive work of the Federal fishery bureau, has reached its present proportions and efficiency en tirely through the application to hatch ing and rearing methods of biological knowledge of the spawning, development, and general natural history of each of the fishes handled-knowledge that has depended on painstaking, long-continued field investigations.