130 BIOLOGY OF PLANTS. 



Sicily and Syria. Its bulb is nearly the size of a human head, 

 is shaped like a pear, and formed of fleshy scales. It has no 

 smell, but its taste is bitter, nauseous and acrid. It is used in 

 medicine to excite nausea and vomiting. 



6. Saffron {colchicum autumnale) is used in medicine for the 

 gout. The tube is egg-shaped, and covered with a brown 

 membranous coat. The recent bulbs have no smell, but are 

 bitter, hot and acrid to the taste. It is poisonous. 



III. Woods. The wood of different trees differs but little 

 in composition; generally about forty-eight or forty-nine parts 

 of carbon, six of hydrogen, and forty-four or forty-five of oxy- 

 gen, are found in one hundred. 



The vegetable fibres in herbaceous plants are similar to the 

 wood of trees. Of these, hemp, flax and cotton are the most 

 important, because of their use in the arts. These sub- 

 stances, however, might, with equal propriety, be regarded as 

 the inner bark. 



Fldx. The fibres of flax are " transparent, cylindrical tubes, 

 articulated and pointed like a cane." It was known to the an- 

 cients, and has been an article of universal consumption. 



Hemp is precisely similar in composition with flax, but has 

 a coarser fibre. 



Cotton is the soft down which envelopes the seeds of differ- 

 ent species of gossypium, from which plant the cotton of com- 

 merce is procured. " The fibres of cotton are transparent, glas- 

 sy tubes, flattened and twisted around their own axis." By 

 this test the^ne linen of Egypt is found to be linen, and not cot- 

 ton, as some interpreters of tlie Bible have supposed. 



" Paper is prepared from hemp, cotton and linen rags. These 

 rags are bleached and reduced to an impalpable pulp." This 

 pulp is spread equally on a wire sieve, and the paper placed 

 upon cloths to dry ; after which it is sized and pressed. 



IV. Leaves. The leaves of plants much resemble each 

 other in appearance, but contain various vegetable principles. 



1. Senna is the leaf of the cassia acuiifolia and ohovata, na- 

 tives of upper Egypt and Nubia. It is a valuable cathartic. 



2. Belladonna is tlie dried leaves of the atropa belladonna, or 

 deadly night shade. It is poisonous, but used in medicine. 



