208 REPORT OF COMMISSIONERS OF IXLAXD FISHERIES. 



great majority of the individuals ultimately died, those that survi\'ed 

 were much undersized. It is probable that half-shading is of little 

 value in preventing the growth of these forms. In the interests of 

 artificial propagation of marine crustaceans it would be highly de- 

 sirable to determine more carefully the influence of light.* 



XVII. The Influence of Food Supply and Injuries. 



Although it has been demonstrated that lobsters which have been 

 starved for a long time are materially smaller than the normals, it is 

 not probable that conditions of food supply have much influence in 

 producing differences in the rate of growth of lobsters under natural 

 conditions of environment in different regions of the coast. In con- 

 sideration of this problem the only question that might be raised is, 

 Do lobsters which live in the neighborhood of large cities or settle- 

 ments, where sewer outlets, refuse from fish factories, etc., are com- 

 mon, gain any advantage from the increased opportunity for food 

 supply? A negative answer must be given, for the truth is that the 

 lobsters seem generally to shun those portions of the coast where 

 fresh water or sewage, or pollution of any sort, enters. Outside of 

 these areas the distribution of food is so uniform that the question 

 of its obtainment can have little or nothing to do with the differences 

 in rate of growth of lobsters in different localities. 



The question of the effect of injury upon the rate of growth has 

 been already briefly considered in the earlier pages of this report. 

 For fuller details on this subject, however, reference may be made to 

 Emmel's ('05) recent publication dealing with the regeneration of 

 lost parts in the lobster, and its relation to the molting process. It is 



*lt has been determined by Gorham. ('03) that, among the diatoms which infest the young 

 lobsters, the most common are Licmophora tinda Grunow, Diatoma hyalinum (KUtzing) Grunow, 

 and Rhabdonema arcuatum (Lygnby) Kiitzing. The first of these attacks the eggs and is most 

 abundant in the larval stages. A certain green alga is also common. Of the protozoans the 

 stalked Ephelota coronata is the most abundant both at Woods Hole and Wickford. At the 

 latter station it has often been in greater abundance than the diatoms. Gorham has also iso- 

 lated a fungus, supposed to be one of the Hyphomycetacae whose life history is not yet known. 

 This fungus, growing inside the body, caused considerable mortality among the young lobsters 

 at Woods Hole. WiUiamson ('04) reports a disease which, it would appear from his description, 

 may be of a similar nature. 



