Aquatic JLite 



27 



of the above-mentioned conditions will 

 reduce the evils of inbreding to a mini- 

 mum. 



There are other factors which influence 

 the development of our tropical friends. 

 We have noted nothing new. Every fish- 

 fellow should know that the resultant of 

 it all may be summed up in three words : 

 Use common sense ! 



Snails in Aquaria 



ALBERT GALE 



I do not know which is the more to be 

 condemned, an aquarium without sub- 

 merged aqueous foliage or one having no 

 pond snails. It is the combined action 

 of these two accessories that gives health 

 to the fishes. The preservation of 

 health is the most essential factor for the 

 longevity of both the vegetable and ani- 

 mal specimens of an aquarium. Health 

 can only be maintained when the sanitary 

 conditions are fairly perfect. Aids to 

 health must be studied in all details. How 

 the removal of deleterious and decompos- 

 ing matter is to be accomplished to keep 

 the water free from contamination is as 

 much a nature-study as that of the plant 

 life or of the other inmates of the aqua- 

 rium. 



Nature has provided scavengers in 

 order to keep her many children clean 

 and free from disease germs. The great 

 sanitary scavengers are the too often dis- 

 carded pond snails. They are very abun- 

 dant in all water holes and sluggishly 

 flowing rivers. The life history of these 

 molluscs is very intricate, and their 

 method of reproduction is no less so 

 They increase with great rapidity. A 

 half-dozen placed in an aquarium wherein 

 there are only herbivorous fishes will be 

 quickly stocked, though the latter may 

 often prey upon them. The jelly-like 

 masses of spawn will be found deposited 



on the under surface of any submerged 

 object and on the side walls of a glass 

 aquarium. When thus deposited these 

 jelly-like masses are fairly transparent, 

 and the interesting transformation of the 

 larva? can be seen with an ordinary hand 

 lens. The first indication of life in the 

 ovum is a small black speck in the centre 

 of the egg sac ; when this breaks the 

 young are set free. If some care be not 

 exercised, many will not be suffered to 

 live to maturity. They are tempting mor- 

 sels for any fish, young or old. If the 

 under sides of the leaves be searched the 

 little jelly-like masses are easily seen, or 

 by passing a blade of Vallisneria between 

 the finger and thumb they can be felt. 

 Take these jelly masses that are attached 

 to the leaf and put both eggs and leaf in 

 a bottle of water ; put the bottle and its 

 contents in a suitable situation, and they 

 will hatch out by the dozen. Their food 

 will be the decaying leaves on which they 

 were hatched. 



Here are interesting phenomena : A lit- 

 tle snail will be seen crawling along the 

 water-film, its body suspended under- 

 neath; the only fulcrum it has is, appar- 

 ently, the air above the film, yet he moves 

 as freely as though crawling on a leaf. 

 Suddenly he will lower himself gradually 

 to the bottom and after a time he will 

 as slowly ascend. He appears to have 

 no foothold. This is one of nature's won- 

 ders. Here is the explanation of the 

 marvel. These pond snails possess spin- 

 nerets, by means of which they spin gela- 

 tinous threads ; there is a small cavity at 

 the upper end of the thread, almost in- 

 visible to the naked eye. These cavities 

 act as small boats, and thus the snails are 

 suspended and enabled to ascend and de- 

 scend at will. 



Always keep snails in aquaria. In ad- 

 dition to their use as scavengers, there 

 many nature studies connected with 

 them. 



