192 American Quarterly Microscopical Journal. 



tained by Russow,* as well as those obtained by HoUe.f In 

 the following notes I mention only the points of structure 

 when I find them differing from Holle's or Russovv's account, 

 or when they are mentioned by neither. As HoUe carefully 

 analyzed earlier literature, the following notes on points not 

 mentioned by him may fairly be considered new. When the 

 species is not mentioned, O. pendunculosum is always meant. 



A.— Root. 



The outer walls of the epidermal cells are not visibly thick- 

 ened in O. pedunculosum, or O. vulgatu?n, L. The parenchyma 

 is uniform and filled with starch and oil. The grumous masses 

 and mycelial threads in the middle parenchymatous cells, de- 

 scribed by Russow and HoUe, I found in about half of the 

 specimens of O. vulgatuin, but in no other species. The xylem 

 of the root is usually on the under side of the bundle, though 

 it is sometimes at the side, and rarely above. The vessels of 

 the xylem were, in nearly every case, reticulated. The protect- 

 ive sheath was not distinctly marked by woodiness, but in 

 longitudinal sections the radial walls were beautifully wavy. 

 The parenchyma of the bundle has little starch, but contains 

 many tears of a brownish-yellow color. 



The roots of O. lusitanicum and O. pendulu?n are like that of 

 O. pedunculosum. In O. pendulum the epidermis is often imper- 

 fect ; the deterioration is caused by fungi. The external wall, 

 when present, is decidedly thickened. In both species the 

 xylem is proportionately larger than in O. pedunculosuyn. It is 

 is large as the phloem. The vessels are more frequently scala- 

 riform than reticulated. 



O. Bergianum, Schldl., a S. African species, has a diarch vas- 

 cular bundle. The xylem is divided into two opposite parts, 

 with the phloem between and partly embracing them. The 

 protective sheath is decidedly woody. 



DESCRIPTION OF PLATE XVI. 



Fig. I. — Transverse section of vascular bundle of 0. pedunculosum. The 

 upper side is toward the center ; x, xylem, p, phlcem. 



Fig. 2. — Transverse section of a vascular bundle in the leaf of 0. penduluvi. 

 The xylem (x) inside and the phloem (^) forms, a ring around it, separated from 

 it, above and below, by parenchyma (t). 



* Histologie der Leit-biindel Cryptogamen. Mem. de I'acad. Imp. de St. Petersbourg, Vll. 

 Surie, Tome XIX., No. t., pp. 117-128. 



t Bau and Entwickelung der Ophioglosseen Bot. Zeit., 1875. 



