Page:The aquarium - an unveiling of the wonders of the deep sea.djvu/152

Rh bubbles, generally from the mouth, but occasionally through the gill-aperture. That animals of aquatic respiration are able for a time to oxygenate their venous blood from air alone is proved by the fact that many Fishes, Mollusks and Zoophytes, are able to survive for a long time a privation of water, provided their respiratory organs be exposed to the atmosphere, and be preserved from becoming dry; while immersion in water from which the oxygen has been exhausted would presently prove fatal.

These little fishes afford another example of the power of mental emotions in changing colours. When pursued and caught with a net, in order to transfer them from one vessel to another, they become of a pale semi-pellucid drab hue, on the back, with three reddish lines. But after they have been put in, they gradually resume their original colour, appearing in a few minutes of a dark iron grey. Doubtless fear produces this change, as it does in some of the Reptiles, the Gecko for example, as I know from observation.

Among the fishes which are now brought to market, the Wrasses are conspicuous for the splendour of their colouring. They have put on their summer attire;—I know not whether, like our humble country belles, they choose Whitsunday as the day of their first appearance in holiday hues, but it was just about that time that the magnificent Ancient Wrasse (Labrus maculatus) first fell under my notice, and