WILD LIFE OF ORCHARD AND FIELD 



The pond-snails hang little globules of transpar- 

 ent gelatine containing a few eggs, or otherwise 

 secure their fry to wet stones, floating chips, and 

 the leaves of aquatic plants. In Neritina, a brack- 

 ish-water inhabitant, the ova, immediately upon 

 being laid, become attached to the surface of the 

 parent's shell, and when the embryo hatches each 

 egg splits about the middle, the upper part lifting 

 off like a lid. In most other cases the young gnaw 

 their way out of the shell. Lastly, the eggs of the 

 stout river-snails of our Western lakes and rivers 

 are not laid at all, but the embryos hatch out in 

 the oviduct. 



"The number of eggs produced," remarks Dr. 

 Binney, "varies in the genera and species in the 

 same proportion as the dangers to which they are 

 exposed are greater or less. Thus, in the naked 

 genera, whose means of protection and whose 

 chances of preservation are much less than of those 

 protected by an external shell, the number is much 

 greater than in the latter." 



Our slugs lay several hundred eggs each season, 

 ovipositing at intervals all summer. 



Under the microscope the translucent egg en- 

 velopes present a beautiful appearance, being stud- 

 ded with glistening crystals of lime, so that the 



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