(6) 



hairs, and a number of these have important economic 

 relations. 



Cotton 



Cotton, by far the most important, economically, of all 

 trichomes, consists of the hairs removed from the seeds of 

 several species of Gossypium, of the Mallow family (Mal- 

 vaceae) . 



The seeds grow in a pod known as the "cotton boll," 

 which splits open when ripe, disclosing the mass of hairs in 

 which the seeds are embedded, usually white, but some- 

 times brown. An attempt is now being made, by crossing 

 and breeding, to secure cotton producing black hairs. This 

 hair is known as the "staple" and the cotton is known as 

 "long staple" or "short staple," according to its length. 

 In some species, the seeds separate very readily from the 

 hairs and come away free from them. In others, the hairs 

 are tightly and permanently attached to the seeds and 

 must be cut off. This is done by a machine known as the 

 "cotton gin," and the operation is known as "ginning." 

 After being ginned, the seeds still have short pieces of hair 

 adhering, known as the "lint." This lint is removed by 

 another machine and is used for various purposes, especially 

 in the manufacture of gun-cotton. 



I. 1 Peribebuy cotton, on the seeds. Produced at Peribebuy, Paraguay. 



2. Tacuaral cotton, on the seeds. Produced at Tacuaral, Paraguay. 



3. Crude Natal cotton. Produced at Natal, South Africa. 



4. A finer quality of the same, removed from the seeds. 



5. San Bernardino cotton, on the seeds. Produced at San Bernardino, Paraguay. 



6. Villa Rica cotton, on the seeds. Produced at Villa Rica, Paraguay. 



7. Colombian cotton. Grown in Colombia, South America. Presented by the 



Museum Association of Newark, New Jersey. 



8. Coton Blanco (white cotton).— The opened bolls of Gossypium arboreum Willd. 



Native of the Orient and cultivated. Collected at Mollendo, Peru, by 

 Albert L. de Lautreppe in 190 1. 



9. The same, the fiber upon the seed. 



10. The same, fiber removed from the seed. 



11. Coton Bruno (brown cotton). — A variety of cotton with brown fiber, attached 



to the seed. Produced at Rio de Puira, Peru. 



1 Numbers 1-23, unless otherwise stated, were presented by the Field Museum 

 of Natural History, at Chicago, Illinois. 



