1-jr. 



TAGE SKOGSHKRG 



//. FoiVier's 

 stifitlion^ on 



III- 



■Irarxxis, Homnrus 

 nnii Carcinuf. 



rooks's law as /or - 

 Hlated by C. II. 

 Fiitvler. 



1/olocyprtd.'^ 



The agreement between the lengths of the first ten larval stages as actually determined 

 by F. H. Herf<k:k and given in Table 25 and the calculated lengths must — when one considers 

 the com pa rat iv el V small number of specimens measured — be described as striking. 



These facts seem, of course, to a great extent to support the idea that the prnici])U' 

 used by W. K. BROOKS for the Stomatopods is of universal application. 



The only writer who has dealt in more detail with this problem is G. H. FowLER in a 

 work, 1909, on the plankton Ostracods collected during the cruise of H. M. S. R e s e a r c h 

 in 1900. The result of this study is particularly noteworthy, as G. H. FOVVLER was of the opinicjii 

 that he could show that the above-mentioned principle applied throughout the whole Halo- 

 cyprid group. It was also applied to Cypridina ( Macrocypridina) castanea' G. S. BraIjY, 

 Homarus americanus MiLNE EDWARDS and Carcinua maenas Leach. 



On p. 224 of this work G. H. Fowleh suggests that this principle should be called 

 ..Brooks's Law", ,,in honour of one of the most ingenious of recent naturalists" and he formu- 

 lates this .law in the following general way: ,,D uring early growth, each stage 

 increases at each moult by a fixed percentage of its length, which 

 is approximately constant for the species and sex." 



The following examples of the applicability of this ,,law" in the Halocyprid group arc 

 given in this work: 



Halocypris globosa (C. Claus). 



Stage 1. 

 Mean 2„')1 



Stage 11. 

 ^lean l,.5'i 



stage V. 

 StayclU Stage IV. ^^^^ 

 Mean 0,9.', Mean 0,61 „,,, 



l.iMii;tli ill mm.: 

 Number of $ measured: 



1,6 

 13 



i,r, j 1.', 



1 I 8 



1,3 

 1 



1,2 

 1 



1,0 I o,y I 0,7 [ 0,6 



4 4 2 9 



0,4 

 1 



Total specimens measured: 315 ?. 



, .Considering the scarcity of the smaller specimens, the response of the mean to 

 Brooks's law is good: —0,37 x 1,62 = 0,59; 0,59 x 1,62 = 0,95; 0,95 x 1,62 -= 1,539; 



1,54 X 1,62 = 2,49" (p. 278). 



Gonchoecia spinifera (C. Glaus). 



stage II. 

 Mean 2.12 



Stage III. 

 Mean 1,'ii. 



Stage IV. 

 Mt:ail O.'.tK. 



Number of 5 measured: 

 Length in mm.: 

 Number ol ^ measured : 



Stage II. 

 Mean 1,80. 



Stage III. Stage IV. 

 Mean 1,'. 1. Me;in 1,03. 



Total specimens measured: 59 ¥ + 32 o- 



,,The females, although few, respond well to Brooks's law: — 0,98 x 1,47 ^ 1,44; 

 1,44 X 1,47 = 2,11. There were only three males at Stage IV., a number which cannot be 



