REPORT OF COMMISSIONERS OF INLAND FISHERIES. 181 



before the uyinter months oj the same year, into the eighteenth stage, 

 experiencing no further change until the following April. 



1. Gradual Diminution in the Percentage of Increase at Molts. 



It is indeed possible, and perhaps probable, that, after the seven- 

 teenth or eighteenth stage, the percentage of increase in length for 

 each successive stage undergoes a gradual, though slight, diminution. 

 If we draw conclusions from observations on the rate of development 

 of most of the marine invertebrates, we must believe that in all cases, 

 as the size of the individual slowly approximates to the average 

 growth limit of the species, the rapidity of development becomes grad- 

 ually less. While among those forms which do not grow by means 

 of an ecdysis, this fact is evinced by a gradual retardation of the 

 growth process, among those animals which do grow by molting, the 

 change manifests itself as a gradually increasing period of time between 

 successive molts and by a decreasing percentage of gain after each suc- 

 cessive molt. And without doubt this natural retardation in the rate 

 of growth is somewhat accentuated by the average number of injuries 

 to which animals with dispositions so pugnacious are always liable. 



On the subject of the rate of growth of lobsters between 5 and 7 

 inches in length we are able to obtain valuable data from Table No. 

 10 B, and from other cases which have fallen under the writer's obser- 

 vation. In many instances it is to be regretted that the unfortunate 

 and premature death of many very valuable individuals has placed 

 some difficulties in the path of observation of certain molts, so that in 

 several cases the deductions must appear to a degree speculative. It 

 is most probable, however, that the majority of estimates, even in the 

 instance of the very large lobsters, do not come far distant from the 

 actual facts of the case. If attention be directed to Table No. 10 B, 

 column 1, it appears that the individual lobsters under consideration 

 did not molt more than once before May 31. Considering that 

 lobsters designated a, b, c, d, e, and a', b', c', d', e' are identical, we 

 can construct the following table, which should give us some idea of 



