A YOUNG NATURALIST. 



275 



from one locality to another, according to the seasons. 

 They are so common on the lagoons which surround the 

 city of Mexico, that sportsmen scarcely will be troubled 

 shooting them." 



While l'Encuerado was preparing dinner, I and rny com- 

 panions walked along the edge of the stream. Before long 

 I discovered some water-cress — a lucky discovery for trav- 

 ellers who are confined constantly to animal food. Lucien 

 examined the small white flowers, which have obtained for 

 all its family the name of Cruciferce ; these vegetables con- 

 tain an acrid and volatile oil, which gives them strong anti- 

 scorbutic qualities. The cabbage (Brassica oleracea), tur- 

 nip (JB. napus), radish (Haphanus sativus), and mustard 

 (Sinapis alba), are of the crucifera order. To this list we 

 must also add the horse-radish, the colza, the seed of which 

 produces an oil well adapted for lighting purposes; the 

 erysimum, or hedge-mustard, a popular remedy in France 

 for coughs ; the shepherd's purse, which the Mexicans use 

 as a decoction for washing wounds; and the Lepidium 

 piscidium, employed by the natives of Oceanica for intoxi- 

 cating fish, so as to catch them more easily. 



" You quite forget the cochlearia, or scurvy-grass, so use- 

 ful to sailors as a remedy for scurvy ?" said Sumichrast. 



" You are right ; but I think I've said enough about the 

 Cruciferce for Master Sunbeam to remember." 



A few paces farther on, while we were looking for insects 

 under the leaves of a shrub, Lucien drew back in surprise 

 at seeing it covered with the pretty little creatures called 

 tree-frogs (Ilyla viridis). Instead of flying towards the 

 water, these reptiles made for the woods. Sumichrast ex- 

 plained to the young naturalist that tree-frogs have sticky 

 disks on their feet, and by the aid of this mechanism they 

 could move about on leaves and even on smooth surfaces. 



"In Europe," he added, "the peasants shut them up in 



