29 



them open nearly to the hack ; gut them ; fill them with 

 coarse salt, and pack them in the same, with the addition of 

 a little saltpetre. 



INSECTS. 



The opportunities for collecting and making observations 

 upon insects will, probahly, he as rare with members of the 

 Mercantile Marine as those for observing and collecting the 

 eggs of Birds. Instructions for preserving zoological speci- 

 mens, however, would be very incomplete without some brief 

 directions relative to this, the most numerous of all classes 

 of animated beings. 



The most profitable service that can be rendered will be, 

 whenever opportunity occurs, to inquire into and secure every- 

 thing illustrating the usefulness of insects to man, with a view 

 to the possible extension of their good services. The silk- 

 moths are a case in point. The Ailanthus silkmoth, long 

 known to naturalists, and for centuries cultivated in China, 

 was introduced to Europe, in 1856, by the Abbe Fantoni, a 

 Piedmontese missionary. It is now cultivated largely and 

 profitably in France, and, being very hardy, is also being 

 reared in England. More than forty species of silk-producing 

 moths have been described by naturalists ; but the majority of 

 the species are very imperfectly known, as to their food, habits, 

 and transformations. Several of these have only been disco- 

 vered within the last few years. Five of the new species are 

 from Japan ; and, as silk-producing moths are widely dispersed 

 through the East, it is quite possible to render important 

 service, by procuring examples of the eggs, caterpillars, 

 cocoons, and perfect insects, of any species known to produce 

 silk, with samples of the silk itself. A yet greater service 

 would be performed by obtaining and carefully conveying 

 home living cocoons, to hatch and breed in this country, and 



