244 
Part III. — Ninth Annual Bejport 
previous data relating to the same species)."^ A certain proportion of the 
ova, taken from different parts of the ovaries, was carefully weighed on a 
chemical balance, and gradually boiled in a test-tube, and the number 
then counted. At first a vulcanite tray divided into equal squares was 
used, the numbers on each square being put down separately ; subse- 
quently it was found more convenient to use a large common writing- 
slate, and to record the numbers in 50's with a pencil held in the left 
hand.f 
Before detailing the number of ova present in the various specimens 
examined, it may be well to consider generally some points brought out 
in the course of the investigation. 
1. Pkoportional Weight of the Ova Compared to the rest 
OF the Body. 
This was determined in every case possible ; but, except in a few 
instances, conclusions based alone upon the data thus obtained would be 
very misleading. As will be seen later, the pressure of reproduction, so 
to speak, and the process of oviposition, vary very much among different 
specie.^. In some cases, as with Cydopterus lumpus^ the whole of the 
season's ova required to maintain the proportional abundance of the 
species may be easily carried in the mature condition by the female, and 
may be all deposited, en masse, within a few hours. In some other fish 
with more or less scattered demersal ova, as the salmon, herring, and 
smelt, the season's oviposition, altliough not so sudden as in the case of 
the lumpsucker, is probably more or less continuous and completed within 
a few days from the commencement of the spawning process ; in ripe speci- 
mens of these species examined, I found all the ova to be practically uni- 
formly developed and equally ready for extrusion. But in probably the 
majority of other fish whose ova are demersal, it would appear that of 
the ova deposited by one female during the course of a single season, only 
a moiety are extruded together — that there are successive crops or layings, 
separated by definite intervals for the maturation of the undeveloped ova 
remaining in the ovaries. This, surmised by HarmorJ to be the case with 
' the stickleback,' has been observed by Ransom to occur with Gasteros- 
teus 27ungitius, § and by Prince with Gasterosteus spinachia.W I have 
examined several fully-developed ovaries of the last-named species, and 
have compared them with the ovaries of a number of other fish having 
demersal ova, with the result that it appears extremely probable that in 
the following species the season's eggs are shed in two or more definite 
crops : — Sijngiiathus aciis, Anarrhickas lupus, Cottiis bubalis, Liparis 
montagui, Ammodytes la7iceolatus. In Liparis and Anarrhichas three 
distinct grades of eggs were found, and in Cottus and Syngnathm 
two. The condition in Ammodytes somewhat resembled that in fish 
* In all cases given in this paper the ' weight of ovaries ' is exclusive of the 
weight of the membranes. 
+ Some of the specimens were sent from the * Garland ' by Mr Thomas Scott, 
F.L.S. ; others by Mr John Murray, the fishery officer at Newhaven, and by Mr 
William Mair, the fishery oflficer at i\nstruther ; and a few were obtained from fish- 
mongers. Professor M'Inlosh was good enough to send some specimens from the St 
Andrews Laboratory. Besides the gentlemen named, I have specially to thank Mr 
Peter Jamieson, the assistant naturalist at the Board's Marine Laboratory at Dunbar, 
who devoted as much time as could be spared from his other duties to procuring 
specimens, especially of the shore fishes. 
X Phil. Trans., vol. Ivii. parti., p. 283, 1768. 
§ Ann. and Mag. Nat. Hist., third series, vol. xvi. p. 450, 1865. 
II Ann. and Mag. Nat. Hist., fifth series, vol. xvi. p. 487, 1885. 
