FORM AND GROWTH IN FISHES 381 



centimeter scale and the length read off directly. Measurements 

 were always read to 0.5 mm. The same scale and balance were 

 used throughout the work. 



Such sources of error as evaporation and post-mortem shrink- 

 age were avoided by weighing and measuring the material imme- 

 diately on its arrival at the laboratory. The surface water and 

 mucus were removed before weighing. After a preliminary in- 

 vestigation, carried out on about half the number of individuals 

 used in this work, it was found unnecessary to apply a correction 

 for the weight of the stomach contents. 



The sources of variation occasioned by the physiologic dis- 

 turbances of spawning (Miescher, '81, and Greene, '14) is, in 

 this case, negligible. None of the specimens showed any pro- 

 nounced development of the gonads, and in many cases it was 

 difficult to determine sex because of the immature or unripe 

 conditions of the sex organs. 



WEIGHT AND LENGTH 



The data obtained are given in part in figures 1 to 5. In all 

 cases weight is given as the ordinate and length as the abscissa. 

 The circlets represent single determinations in most cases, al- 

 though there are many duplicates and even triplicates. The 

 individuals of each species show a clear correlation between the 

 weight and the length. Since the circlets represent males and 

 females in about equal numbers, and since these are well dis- 

 tributed about the smoothed curve, we may conclude that sex 

 does not influence the constant relation between weight and 

 length. 



This agrees with what has been shown to be true for the 

 weakfish (Crozier and Hecht, '14) and for the dogfish (Hecht, '13), 

 also with Heincke's results on the European plaice. Donaldson 

 ('12) states that in the albino rat, differences in sex are negli- 

 gible in the relation of total weight to length as well as to weight 

 of brain and of spinal cord. Although not explicitly stated, the 

 figures given by him (Donaldson, '98) for the frog, lead to the 

 same conclusion. 



