33 
the outside of the egg membranes, and thus increasing 
their specific gravity beyond the point capable of floating 
in the water. On several occasions when the supposed 
dead embryos were examined, it was found that they were 
alive, and, on the removal of the coating of fine mud, the 
embryos again floated freely on the surface of the water. 
‘Towards the close of the hatching experiment, the 
water was passed through an ordinary flannel] jelly bag 
before being allowed to enter the tanks, and by this 
means it was found possible to entirely remove the 
suspended matter, the water passing into the various 
vessels in a perfectly transparent condition; but, owing 
to the lateness of the season, and the arrival of workmen 
to make the necessary alterations for converting the pre- 
mises into our present hatchery and laboratory, no further 
hatching could be tried with the filtered water. 
‘ Besides the fish hatching experiments now described, 
other investigations were carried on as well, and these 
included visits made from time to time to the various 
shell-fish beds in the neighbourhood, for the purpose of 
examining their condition and collecting samples for 
working at in the laboratory and for testing the water in 
the tanks. We had, therefore, many economic marine 
animals living satisfactorily in the tanks during the two 
months; these consisted of various kinds of fishes, includ- 
ing small Soles, Plaice, and Dabs ; shell-fish, including 
Mussels and Cockles, and also a couple of Oysters found 
living in the vicinity ; Crustacea, including Shrimps, 
Lobsters, and Crabs, and other invertebrates which, 
although not directly valuable, are yet indirectly so, from 
the part they play as the food of other marine animals. 
Many of the Shrimps were egg-bearing females, and the 
more mature ones were taken from amongst the others 
and kept in separate vessels; so on seyeral occasions we 
