Ee SS heer Ee BAGKk 
(Gastrosteus aculeatus) 
Tue illustration given (Fig. 209) is the natural size of the three-spined 
stickleback. There are said to be several kinds, but the above is 
the one which is most plentiful all over Scotland. Every stream, 
river, and ditch contains them, and they are also got in the sea all 
round our coasts. They spawn in June, but before doing so a 
rough nest is made, in which the female deposits her eggs. These 
are hatched in from twenty-one to twenty-five days. While the eggs 
are in the nest the male becomes very brilliantly coloured. His 
belly is scarlet, his sides silvery, and his back yellow and green; the 
female, on the other hand, is usually of an olive green. He then 
keeps a strict watch over nest and eggs, and allows no intruder to 
come near. 
By December the young are about three-quarters of an inch 
long. I have on many occasions kept them in a glass globe along 
with minnows, but the stickleback always killed the former. The 
usual mode of attack was to swim close up to the minnow with fins 
spread out and to dash at it sideways, using the hard spine in striking. 
The minnow slipped out of reach for a moment, but the stickleback 
renewed the attack in the same way three or four times, after which 
the minnow fell lifeless to the bottom of the glass. The greatest 
number of sticklebacks I have seen was at the outlet of Loch Leven. 
Here they are drawn through the sluices, and being unable to re-enter 
the loch, the water at this part literally swarms with them. 
If a new loch is made or an old one enlarged these interesting 
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