78 



NATURAL HISTORY 



with the vinegar, no eels will be found : this is often 

 added by the maker, to prevent mildew. 



125. Vibrio glutinis [Anguillula Jlaviatilis, E.) The 

 paste Eels. — These interesting microscopic objects are 

 described in the *' Microscopic Cabinet/' and illustrated 

 by some magnified drawings by Dr. Goring; I shall 

 therefore only append here some additional observations, 

 and refer the reader to that work for further information. 



If you select a number of the full-grown eels, and wash 

 them in clean water, to free them from the glutinous 

 matter of the paste, and then place them in an aquatic- 

 box, or on a stage-glass, under the microscope, with a 

 magnifying power between 200 to 400, the sexual organs 

 may be distinctly recognized when the eels are quiescent. 

 This, as well as their internal organization, will be more 

 readily discerned, if a drop of a mixture of carmine be 

 introduced to them. 



One of the most striking peculiarities in the economy 

 of these creatures is, that the female at one season of 

 the year is oviparous, while at another, she is vivipa- 

 rous. (See " Microscopic Cabinet," Plate 4.) The object 

 of these changes is unknown ; but I conceive it probable 

 that the eggs are produced for the continuation of the 

 species through the winter ; as we have well authenti- 

 cated experiments on the eggs of insects, which shew 

 that no ordinary cold injures their vitality, although it 

 may be so intense as to retard the exclusion of the young 

 for several years. Some observers consider the ovipa- 



