Ill] THE WEIGHT-LENGTH COEFFICIENT 101 



RelMion of Weight to Length in Plaice of 55 cm. long, from Month 

 to Month. {Data taken from the Department of Agriculture 

 and Fisheries' Plaice- Report, vol. ii, p. 92, 1909.) 



With unchanging length, the weight and therefore the bulk of the 

 fish falls off from about November to March or April, and again 

 between May or June and November the bulk and weight are 

 gradually restored. The explanation is simple, and depends 

 wholly on the process of spawning, and on the subsequent building 

 up again of the tissues and the reproductive organs. It follows 

 that, by this method, without ever seeing a fish spawn, and without 

 ever dissecting one to see the state of its reproductive system, we 

 can ascertain its spawning season, and determine the beginning 

 and end thereof, with great accuracy. 



As a final illustration of the rate of growth, and of unequal 

 growth in various directions, I give the following table of data 

 regarding the ox, extending over the first three years, or nearly 

 so, of the animal's life. The observed data are (1) the weight of 

 the animal, month by month, (2) the length of the back, from the 

 occiput to the root of the tail, and (3) the height to the withers. 

 To these data I have added (1) the ratio of length to height, 

 (2) the coefficient (k) expressing the ratio of weight to the cube of 

 the length, and (3) a similar coefficient {k') for the height of the 

 animal. It will be seen that, while all these ratios tend to alter 

 continuously, shewing that the animal's form is steadily altering 

 as it approaches maturity, the ratio between length and weight 



