THE ALLIACEOUS PLANTS. 



117 



through the winter, afford young onions through the spring, and the 

 remainder being either thinned or transplanted into rich soil produce 



Fig. 163. — Underground Onions, \ diam. 



Fig. 164. — Globe Tripoli Onion, \ diam. 



by August fine bulbs. These onions attain much larger size if the soil 

 between them is stirred, and small quantities of guano be given to them. 



The best kinds for this purpose are the Flat and Globe Tripoli, 

 the Rocca, and Spanish onions. We have grown the Globe Tripoli 

 (fig. 164) nearly two pounds in weight, but at Naples they have 

 attained nearly four pounds in weight. The third or main crop is 

 sown in March, and when ripe is stored .for winter use. The Spanish 

 and blood-red are best for this crop. The fourth or last crop is 

 cultivated to produce little tubers for pickling. 

 Our soil is not well adapted to produce little 

 onions, and we succeed but badly with them, 

 probably from its being too damp. The cells of 

 the skins of onions' have crystals in them (fig. 

 165), which may be seen when examined under 



the microscope. We have occasionally had the K„,.x6s.-Crj.staismOnio„. 

 tree onion, a variety which produces little onions at the tops of stalks. 

 They are coarse and strong, and of no horticultural importance. 



We always cultivate the Leek {Allium Porrum, fig. 166), which 

 is a choice vegetal in early spring. It is the hardiest of all the 

 hardy plants of the garden, standing the severest frost with impunity 



