Practicurns 



17 



(sativus is Latiu for planted " or " cultivated A. fistulosiim, 

 A. Cepa, and others. 



The naming of the species and the botanical forms of plants 

 follows a system characterized by great precision and regu- 

 larity. It is well for the student to understand the main ele- 

 ments and practices in it, for he is not only enabled to under- 

 stand but he is trained in accuracy and carefulness of record 

 and reference. 



For the most part, English measurements are used in the 

 descriptions. In the minuter weights and sizes, however, 

 metric denominations must, be employed. The lowest denomi- 

 nation in avoirdupois weight is one grain, but this denomina- 

 tion is 50 times too heavy to weigh a mustard seed. The 

 gfain in apothecaries' or troy weights is still heavier, for there 

 are only 5,760 grains in 1 lb., whereas in avoirdupois weight 

 the pound is divided into 7.000 grains. Therefore, the milli- 

 gram (mg.) is used for the weighing of seeds. A commer- 

 cially dry seed of black mustard weighs about 1 mg. (say ly^ 

 mg.) ; so does a small-sized dry turnip seed, w^hile a large turnip 

 seed weighs about 2 mg. There are 1,000 mg. in 1 gram. The 

 pictures of the seeds in this book are mostly enlarged. The flat 

 or rectilinear dimensions are indicated by the figure in paren- 

 thesis : (X4) means that the picture is 4 times broader and 

 longer than the seed ; ( x i/4 ) that the picture is only one- 

 quarter as large as the natural object. Seeds and seedlings 

 are likely to differ between marked garden varieties or races. 



THE TLAX OF THE BOOK 



The arrangement of the book may now be explained. After 

 the introductory chapter, defining the subject-field, the dif- 

 ferent vegetables are taken up in groups. They are discussed 

 in groups so that related crops may be considered together, 

 avoiding considerable repetition of advice and contributing to 

 a clearer understanding of the subject. Thus, all melons, 

 cucumbers, squashes, are closely related in cultural require- 



