300 BULLETIN OF THE BUREAU OF FISHERIES. 



and k denotes a constant, according- to La.tastg?3lTtN.relatinn of these quantities would 

 be expressed by the following equation:^ 



N 

 Whence k=-j=. 



He has drawn up a table (based on table 15 0^149), from the data of which he 

 deduces the cubes of lengths, the ratiosofthe^Afefage number of eggs to cubes of length 

 (k), and the means of these ratios. 



In the lobster the reproductive powers are manifested suddenly at a certain age, 

 after which they increase steadily, reach a maximum, and then presumably slowly 

 decline. Accordingly during the first period only does the fertility increase proportion- 

 ately to the increasing volume of the body, as expressed in the equation given above. 



We have no definite information upon the duration of life, or decline of rate of 

 growth in these animals. It is certain, however, that the renewal of the shell is 

 quite as necessary for the continuance of life a s of growth, since in the course of time 

 death would result were not the injured and abraded shell restored. In higher animals 

 the skin and at least some of the tissue cells are being continually renewed throughout 

 life, while size limit of the body is early attained, and it is not likely that a dense and 

 heavy shell like that of the lobster could be sloughed without increase in the size or 

 volume of the body. The decline in sexual vigor may therefore result from the tax 

 which molting continues to levy upon the capital stock of energy at every period of 

 life. According to Lataste: k=f (t), k being a function of age which has no real value, 

 except as it is confined within certain limits. 



In conclusion, we wish to observe that upon the principle of correlation of parts 

 the ratio of the number of eggs to body length should correspond in a general way (o 

 the ratio of the volume of eggs to the total volume of the body were the latter a con- 

 stant quantity, but owing to the frequent loss of the great claws this is not accurately 

 represented by the cube of the length. All that we can say is that in the long run 

 there is a tendency to produce in such a ratio, but the physiological condition of the 

 animal is an inconstant and indeterminable factor. The high birth rate of the lobster 

 teaches us to expect a correspondingly high death rate, a subject which will be later 

 considered. 



BREEDING HABITS AND BEHAVIOR IN CRAYFISH. 



The breeding habits of lobsters, so far as they were then known, were described 

 in 1895. Since that time a number of important facts have been ascertained, but 

 our knowledge of the subject is still defective at many points. The behavior of the 

 American lobster at the time of pairing and extrusion of the "eggs has probably never 

 been witnessed in a state of nature, and certainly but seldom in any of the higher Crus- 

 tacea. We have had more or less circumstantial accounts from Chantran, Ishikawa, 

 and Cano, regarding the time and process of egg laying in the crayfish, shrimp, and 

 crab. The pairing habits and process of laying the eggs in the Buropean lobster have 

 been described by Anderton and Scott, as will be noticed later, while a remarkably 



