262 REPORT OF COMMISSIONERS OF INLAND FISHERIES.. 



parative results becomes evident when it is considered that both 

 the stage of the lobster and the season of the year greatly modify 

 the length of the period between molts. 



The specimens selected in this way were next separated into two 

 groups. The specimens of one group were then mutilated, while the 

 lobsters in the other group were kept in a normal condition as con- 

 trols. The molting period of normal individuals thus served as a 

 standard with which to compare any variations in the molting of 

 the other specimens, caused by the mutilation and resulting regenera- 

 tion. 



The nature of the mutilations was also considered, for it is highly 

 important, in comparing results, that the character and degree of 

 injury be uniform. The recjuisite uniformity of the mutilations in- 

 the lobster is easily obtained. By means of a special structure at 

 the base of the legs and chilipeds, these limbs, when injured, are 

 always thrown off by the animal at this particular region or breaking 

 plane, a process known as autotomy.* In the present experiments 

 the mutilations were made by crushing the tip of the limb with 

 forceps, and in every case the limb was dropped at the moment of 

 injury. It is from the stump remaining after autotomy that another 

 limb begins to bud and regenerate. 



It was attempted to conduct the experiments under conditions 

 as nearly normal as possible. Both mutilated and normal lobsters 

 were kept in cylindrical boxes with earthenware saucers, six inches 

 in diameter, at the bottom, and these were suspended in the water, as 

 shown in Plate XL. Thus each cylinder provided a free circulation 

 of water. The lobsters were fed on minced clams and fish. A canvas 

 awning was placed over all the cylinders, and every precaution was 

 taken to keep the specimens in as nearly a natural environment as 

 possible. 



Observations were made three times every day, morning, midday^ 

 and evening. A record was made of the date of molting for each 



*See Emmel, " The Regeneration of Lost Parts in the Lobster." Report of R. I. Com- 

 mission of Inland Fisheries, 1904, pp. 88-89. 



