34 . TRANSACTIONS OF THE [ Sess. LXXIII. 
authorities and to Mr. Rourke, superintendent of the gardens 
there, for some valuable material. 
Mr. W. E. Evans, B.Sc., very kindly made slides from 
sections illustrating the attack. 
To my friend Dr. Ashworth I have been greatly obliged 
throughout. He has helped me in the identifying of the 
parasite, in searching for literature, by several discussions, 
and by the loan of slides of the life-history of H. schachti, 
Schmdt., which were shown to the Society when this 
communication was first read. 
REFERENCES. 
(1) Drs. Levoxarr and Nirscun, Erkldrungen zu den zool. 
Wandtaf., Cassel, 1877. 
(2) C. Craus, Lraité de Zoologie, 12th French edition. Ed. 
by Moquin-Tandon, Paris, 1884, p. 527. 
(3) Sepewicr’s Student's Text-Book of Zool., vol. i., London, 
1898, p. 290. 
(4) Vurttemin et Lucrain, ‘“‘Symbiose de l’Heterodera radici- 
cola avec les plantes cultivées au Sahara,” C. R. Acad. Se., exviil., 
1894, p. 549. 
(5) Cambridge Nat. Hist., vol. ii. pp. 154-156. 
EXPLANATION OF PLATES. 
Puate LV. 
Fig. 1. T.S. of Normal Bromeliad root, near endodermis. Bzllbergia 
pallidiflora, 
2. T.S. of root (from large vas to inner cortex) near attack 
of Heterodera sp. 8. pallidiflora. 
,, 3. Hypertrophied protoxylem. J. pallidiflora. 
,, 4 Pith and vasa. Thickening inhibited. B. Saundersiz, 
» 9. Attacked vas to show parenchymatous walls persistent. 
Pitewirnia corallina. 
t.c. Inner cortex. ph. phloem. 
e. endodermis. p.«. protoxylem. 
p. pericycle. v. vas. 
t.p.c. thickened pith-cells. w.p.c. unthickened pith-cells, 
uv.p. xylem parenchyma, 
