of the Fishery Board for Scotland. 



253 



occurs at all stages, whilst the sprat is only found in very small number*. 

 Amongst pleuronectids the witch and lemon dab may be noted. 



The bottom-nets gave a very few young fishes, which were principally 

 gadoids and sand-eels.- Clupeoids are here markedly absent, though a 

 few occur at the inner stations in the Moray Firth. 



Beyond these few observations nothing more can be added about this 

 important area until more extended observations have been taken there. 

 Of the remaining divisions of the East Coast, the Aberdeen and Montrose 

 Districts have received up till now a passing atteution, and only a few 

 superficial notes are recorded concerning the ova found in these regions. 

 Finally, in the region of St Andrew's Bay matters are in a very different 

 condition, and its pelagic fauna has been so fully reported elsewhere that 

 nothing can be added here. 



Experiments on Preservative Solutions. 



Experiments, with a view to discovering a satisfactory and simple 

 method of killing and preserving pelagic ova, were renewed at the 

 Laboratory this year. A number of fresh and dead ova were hardened 

 in various solutions, and preserved in other solutions for periods extend- 

 ing over several months, and the condition of the ova was carefully 

 observed from time to time. Measurements were taken before and after 

 the various stages of the experiments. 



Amongst killing reagents used, the only one which gave at all satis- 

 factory results was the solution which was found to be successful last 

 year also — namely, a saturated solution of picric acid in 5 per cent, hydro- 

 chloric acid. The ova are exposed to its action for about three minutes, 

 when they may be removed to the preserving fluid directly without any 

 washing. Experiments seem to show that a great part of die contraction 

 which always takes place is due to the process, formerly persevered in, of 

 washing with water. A slight washing with the preservative fluid itself, 

 may, however, be of advantage. 



Corrosive sublimate, as a killing reagent, does not seem to have any 

 advantage over the above in the way of contraction or condition of the 

 embryo, and it has the great drawback of rendering the yolk and embryo 

 densely opaque. 



As regards preservative fluids, the one which seemed most satisfactory 

 last year, namely, picric acid 1 part, methylated spirit 1 part, and 2 per- 

 cent. ace,tic acid 1 part, after the experience of continual usage, cannot be 

 recommended. The shrinkage was about the same as in 60 per cent, 

 spirit, namely, an average of about 10 per cent, diameter in eighty days, 

 but in some cases the extent was uncertain, whilst the injurious effect of 

 the picric acid upon instruments and upon the operator makes it an ob- 

 jectionable reagent. Its effect in darkening and rendering more distinct 

 the oil-globule is undoubted, but this effect may be obtained to as great 

 a degree as is necessary by the use of the same reagent in the killing fluid 

 recommended above. 



In a solution consisting of equal parts of alcohol and acetic acid (2 per 

 cent.), the average shrinkage in forty-eight days was about 10 per cent., and 

 this increased in eighty days to about 18 per cent, for the larger eggs like 

 long rough dab, the smaller eggs not shrinking further. The eggs were 

 well preserved, but the yolk tends to opacity, as in the 60 per cent, pre- 

 paration. The oil-globule remains a transparent yellow (usually), and is 

 fairly distinct. Towards the end of the eighty days, some of the eggs 

 showed a tendency to blackening. 



, In a solution of 4 parts alcohol, 4 parts acetic acid (2 per cent.), and 1 

 R 



