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at the transition from Stage II to Stage I and between the latter stage and the mature stage.
57 d: 51 d = 1,108; 62 d: 57 = 1,109.
Cypridina (Vargvla) norvegica: In this the agreement between the theoretically calculated
lengths and those actually observed may be said to be surprisingly great. Here too the males
increase somewhat less rapidly at the change to the mature stage; 3,27: 2,81 = 1,16.
Philoniedes globosa: The agreement between the theoretically calculated lengths and
those actually observed is striking; only the oldest larval dass of lengtli is somewhat longer than
it ought to be theoretically.
Krithe sp. : In the case of this species too it can be said that the growth at the different
moults is very similar. The relations between the mature stage and the oldest larval stage, between
the latter and the next oldest larval stage, between this and Stage III and between Stage IV and
Stage V are really very similar, 1,24 — 1,254 ; average, 1,245. Only at the transition from Stage IV
to Stage III does the growth seem to have been less, the growth-factor being 1,21.
In passing I may point out liere that a smaller number of specimens of the investigated
material of this species might have given a considerably more striking agreement with ßHOOKS’s
law. Growth-factor = the average fourni above, 1,245.
15,5
15,5 X 1,245 = 19,29
19,29 X 1,245 = 24,0
24,0 X 1,245 = 29,88
29,88 X 1,245 = 37,2
37,2 X 1,245 = 46,3.
In other words, if we use this growth-factor, we obtain theoretically average lengths,
all of which are within the boundaries of the length classes that were established empirically.
In passing I may point out here that other Ostracod species as well, of which unfortunately
I had at my disposai only a rather slight material, showed a good agreement with BROOKS’s
law. I shall only mention a single one of these here, as it gives a rather good illustration of the
applicability of this law.
In a tube of Ostracods from the Falkland Islands that I investigated there were,
besides mature specimens of a Cythereis species* not previously described, a number of larvae
which, in spite of a number of differences, were, on fairly good grounds, assigned to the above
species. At the locality in question the mature specimens of this species were characterized
by great constancy with regard to the length of the shell; mature males – 0,80 — 0,83 (usuallv
0,83) mm. Mature females = 0,77—0,79 (usually 0,78) mm. A number of the larvae in quest i< >n
measured 0,49—0,51 (average 0,50) mm., others 0,40 mm. For anatomical reasons 1 concluded
that they represented Stage II and Stage III. The growth-factor was consequently 1,25.
0.40
0,40 X 1,25 = 0,50
0,50 X 1,25 = 0,625
0,625 X 1,25 = 0,781.
* To be described in a later part of this work,
Zoolog, bidrag, Uppsala. Suppl.-Bd. I.
An additional
example tn favoue of
this law.
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