T II B EE- S T I N ED STICKLEBACK. 
r Plie tubular chamber is constructed, and the form and 
durability of the whole nest attained, l>y r the Stickle- 
back swimming slowly over the parts already in po- 
sition, and at the same time gluing them together 
and cementing them. Evers distinctly observed how 
the builder, when he had added new layers, shook his 
tins, raised his head, bent his body upwards, and slid 
his belly over the structure, emitting at the same time 
a drop of a viscid substance, which could be clearly 
distinguished in the water, and the effects of which 
might immediately be perceived in the now cemented 
building-materials". At times he shook the building 
and then pressed it together again; at times he kept 
swimming over it. With his fins, which he kept in 
continual and rapid motion, he produced a current, 
and thus washed away from the nest the pieces that 
were too light and the loose stalks, which he then 
took up again and tried to fit in more durably. It 
took about- four hours to procure the various building- 
materials; but at the expiration of this time the out- 
lines of the nest were ready. Its completion, the re- 
moval of the parts that are too light, the arrangement 
of the separate stalks, the plaiting of their ends, and the 
addition of the sand to weigh them down, require several 
days. While the Stickleback is building his nest, he 
thinks only of his work and endeavours merely to pro- 
vide against any interruption in its progress or hind- 
rance to its completion. He labours indefatigably and 
watches with suspicion every creature that approaches 
the nest with or without evil intentions, whether it be 
another Stickleback, a newt, a water-beetle, or a larva. 
A water-scorpion ( Nepa ) in one of Evers’ aquaria was 
seized by the cautious builder thirty times or more, and 
carried in his mouth over to the opposite side of the 
aquarium. 
The size of the nest varies pretty considerably, de- 
pending both on its situation and on the materials of 
which it is composed. As a rule it seems to be of the 
size of one’s fist. It is generally ellipsoidal and entirely 
closed above, but furnished at the ends with an en- 
trance and an exit. At first only the entrance is 
visible, but subsequently, exactly opposite it, we dis- 
cover the exit. When the Stickleback has finished his 
655 
building-operations, he endeavours to attract a female 
to the nest. Warrington says that a completed nest 
excites the attention of the female; but Coste asserts 
that the male sallies forth to guide her thither, and 
that he ushers her into the nest with a shower of ca- 
resses. The last statement, however, is also accepted by 
Warrington. The male distinctly shows his delight at 
the arrival of the female, swims round her in all di- 
rections, enters the nest, sweeps it out, returns in a 
moment, and tries to drive the female in by thrusting 
at her from behind with his snout. If she will not 
obey of her own accord, he also employs his spines, 
or at least his caudal fin, to overcome her reluc- 
tance; but in case of need another female is fetched. 
If tlie male succeeds in persuading a female to enter 
the nest, she lays a few eggs within it, according to 
Coste only two or three, and then bores a hole through 
the wall of the nest on the side opposite to the en- 
trance, and departs. The second opening in the nest 
does not exist until it is formed in this manner. The 
current that now flows through the openings, is of 
benefit to the eggs. On the following day the male 
sets out again in quest of a new female, whom he com- 
pels by kindness or force to lay eggs, and repeats this 
process until a sufficient number of ova is procured. 
During or immediately after the laying of the spawn 
he enters the nest, rubs his side against that of the fe- 
male, and then glides over the eggs in order to ferti- 
lize them. 
From this hour his zeal and watchfulness are re- 
doubled. He has to guard and defend the eggs against 
every aggressor. Every Stickleback that approaches is 
furiously attacked and put to flight, whether it be a 
male or a female, for both are equally dangerous ene- 
mies of the eggs, and the latter is perhaps even more 
greedy of the ova or the new-hatched fry than the 
former. Until the young have emerged from the eggs, 
the male shows his care in other ways as well. With 
his mouth he repairs every damage to the nest, and 
often stations himself in front of or within the cham- 
ber, keeping his pectoral fins in vibration and thus 
renewing the water in the nest, as though he knew 
that- the eggs require fresh oxygen. 
" M6bius ( Nature , vol. XXXIX, No. 998, Dec. 13, 1888, p. 168) saw the male .Stickleback keep spinning round the nest new threads, 
which originated from the urinary bladder. The chemical reactions showed that these threads consist of mucin, which is secreted, however, 
not by the urinary bladder, but by the kidneys. The section of a kidney, treated with osmic acid and coloured with hematoxylin, showed 
that only a few of the cells lining the tubnli urinifevi partake in the development of the mucin, while most of them do not undergo any 
change of this description. After the end of the spawning-season, no mucinous cells can be' found in the kidneys, which are now less tumid. 
Scandinavian Fishes. 
