509 
Pedicularis vulgaris, Tournef 
in Pedicularis is for these cells to possess nuclei. Fig. 5, B, represents an 
optical section of a phloeotracheide which shows spiral thickening l. y and 
dense protoplasmic contents with granules g., and a nucleus n. Fig. 5, c, 
shows two of these cells in transverse section, one of which has included the 
nucleus n and the other not. In Fig. 5, D, is depicted a fairly large 
phloeotracheide of the tracheidal plate in obliquely transverse section. The 
nucleus was not included in this section. 
Previous records of these granules in tracheides have been made by 
Heinricher 1 and Benson. 2 Heinricher pointed out their presence in the com 
€ D 
Fig. 5. A. Detailed drawing of cells of penetrating piliferous layer of haustorium, one of which, 
p.t., has become lignified. x 472. b. Detailed drawing of optical section of cell of ‘nucleus’ which 
has become lignified. x 472. c. Transverse section of cells of nucleus which have become lignified. 
x 472. D. Obliquely transverse section of element of tracheidal plate showing protoplasmic 
contents and granules, x 472. p.t . = penetrating tracheidal element ; p.e. = unlignified penetrat- 
ing elements of piliferous layer; p.c . = protoplasmic contents; g — granules in protoplasm; l. — 
lignification ; n. = nucleus of cells. 
ducting cells of Lathraea haustoria , and figures some of these cells in Taf. IX, 
Fig. 7, and Benson describes them in Exocarpus , and considers that phloeo- 
tracheides are characteristic of all root haustoria, though they are arranged 
in different ways in haustoria of different plants. She considers the presence 
of the granules to be due to the deposition of the surplus of hydrated 
cellulose contained in the elements at the time of their lignification. In all 
the lignified conducting cells of this species of Pedicularis examined, not 
1 Heinricher : Anatomischer Bau und Leistung der Saugorgane der Schuppenwurz-Arten. 
Cohn’s Beitrage z. Biol. d. Pflanzen, Band 7, ii, 1898. 
2 Benson, Margaret, 1 . c., p. 671. 
M m 2 
