24 TRANSMISSION OF SPECIMENS. 



prompt aeration of the water around them. This 

 is most readily effected by means of the Syringe, 

 as I shall presently describe. 



If you can so arrange matters, it will be a useful 

 caution to allow your plants exclusive possession of 

 the Tank for a week or two ; not putting any 

 animals in, until you see bubbles begin to form 

 all over the sides, bottom, and rock-work, when 

 the sun4ight shines on them. This appearance 

 will indicate a growth of incipient vegetation, which 

 will greatly lessen the chance of death when the 

 animals are introduced. 



Finally, be moderate in your desire of dominion. 

 Do not overcrowd your Tank. It is far better to 

 have it but half occupied at first, and to add to its 

 population from time to time, than, by a too eager 

 desire to see it filled, make it a Black Hole of 

 Calcutta, and mourn over a host of corpses, the 

 wreck, perhaps, of a single night. Half-a-dozen 

 animals, averaging the bulk of a periwinkle, or a 

 moderate-sized Sea-anemone, to every gallon of 

 water, are quite enough to begin with. 



