MODES OF REPRODUCTION 325 



Parental instincts are exhibited by several of the shore fishes 

 which are common on the British coasts. One of the most fre- 

 quently observed cases is that of the Lump-sucker (Cyclopterus 

 lumpus), whose spawn is attached in large masses in crevices 

 of the rocks above the level of low water at spring tides. The 

 individual eggs are rather large varying from 2 - 2 to 2*5 milli- 

 metres in diameter, the average being therefore about one-tenth 

 of an inch, while the clumps of spawn are sometimes of extra- 

 ordinary size, measuring as much as a foot in length, eight 

 inches in breadth and three or four inches in thickness. It is 

 not certain however that a mass of such large size is the product 

 of a single female. The fresh-laid spawn is more or less brightly 

 coloured, the tint being often a distinct bluish-red or a delicate 

 pink, in other cases it varies from dark to light yellow. The 

 surface of the egg-clumps is not uniform but is broken by large 

 conical depressions which allow the water to penetrate into the 

 interior of the mass ; these pits are made by the male which 

 presses his head into the mass when it is first deposited before 

 the adhesive secretion which holds the eggs together has 

 hardened. (Plate XXVII., A.) The effect of this action is 

 twofold ; it presses the spawn firmly into the crevice of the rock 

 and gives it a firm attachment, and it prevents the eggs being 

 crowded together too closely so that the central ones would be 

 suffocated. The male parent fertilises the eggs at the time of 

 their extrusion by the female, and then remains near them and 

 guards them with constant care until they are hatched. He re- 

 moves any animals such as starfishes, crabs, or molluscs, which 

 crawl on to the spawn and fearlessly defends his charge against 

 any enemies, such as other fishes, which threaten to devour it. 

 Dr. Ehrenbaum, who studied the habits of the fish on the shores 

 of Heligoland, where it is very abundant, states that he saw a 

 male bite the finger of a fisherman who tried to take the spawn 

 out of an aquarium, so severely as to draw blood. From time 

 to time the male which is guarding a mass of spawn, pushes his 

 head into one of the depressions which have been described 

 above and sends a powerful stream of water through the mass by 

 a reversal of his respiratory movements. It appears therefore 

 that the successful hatching of the majority of the eggs is due 

 to this artificial method adopted by the male parent for supply- 

 ing them with oxygen, and that the natural movements of the 



