98 



BOTANY. 



(6) One-celled simple liairs may be obtained from the vegetative 

 organs of species of CEiiotliera and Srassica and many grasses — e.g., 

 species of Panicum — and from the seeds of the cotton plant ; the last 

 constitute the " cotton" of commerce. 



(c) Many-celled simple hairs occur on the filaments of Tradescantia, 

 on leaves of the Primrose, Ageratwm, Erigeron Canadenae, pumpkin, 

 and very many others. 



(d) Branched one-celled hairs occur in Capsella, Draha, Baymbryv/m, 

 Alyamm, and many other Oruciferm. 



{e) Branched many-celled hairs may be found on the Mullein and 

 Ivy. 



Fig. 88.— Hairs from Thistle (Onims alHssimus). A, young hair from the stem 

 before it has been drawn out ; 2), an older hair more highly magnified, after its ex- 

 tremity has been drawn out into a thread-like lash ; C, nair with a long lash from 

 the underside of a full-grown leaf. Highly magniied.— After Beal. 



(/) Clustered or tufted hairs are found on many MaXvaeem, and the 

 nearly related scales or peltate hairs on Sheplierdia. 



(g) Root-hairs are best obtained for study by growing seeds of mustard, 

 radish, wheat, etc., on damp cotton or blotting-paper, and then mak- 

 ing careful longitudinal sections of the terminal portion of the root at 

 the place where the hairs are just appearing (usually several millimetres 

 above the tip of the root). By making preparations in this way all 

 stages of the development of these hairs may be studied in the same 

 specimen. 



(h) Glandular hairs are found in many groups of plants ; they may 

 be studied in Petunia, Verbena, Primula, Ma/rtynia, and the, tomato. 



(j) Apparently related to glandular hairs are the curious hairs from 



