Histogenesis in Roots of Nothofagus — Arnold 
99 
Fig. 5. Outline sketches of transverse sections of 
three mycorrhizas showing range in reduction of di- 
ameter and cell number, m, Mantle; e, epidermis; o, 
hypodermis; c, cortex; n, -endodermis. 
hypodermis of mycorrhizas of N. solandri var. 
cliff or tioides it is suggested that the hypodermis 
plays an important role in preventing the fur- 
ther penetration of the fungus into the inner 
tissues of the root. 
SUMMARY 
The root apical meristem of Nothofagus so- 
landri var. cliff ortioides (Hook, f.) Poole is 
similar to that of Fagus sylvatica. 
In both genera the organization of meri- 
stematic cells which give rise to epidermis, cor- 
tex, stele, and rootcap is basically unaltered by 
mycorrhizal infection. 
However, the subsequent maturation of tis- 
sues in mycorrhizas and non-mycorrhizal roots 
differs considerably. 
A noteworthy feature of mycorrhizas of N. 
solandri var. cliff ortioides is the lack of proto- 
plasmic content of the hypodermis, and its 
striking mode of differentiation from the pro- 
meristem. 
It is suggested that the hypodermis plays an 
important role in excluding mycorrhizal fungi 
from further penetration of Nothofagus roots. 
REFERENCES 
Arnold, B. C. 1959. Isolation of a fungus 
from mycorrhizas of Nothofagus cliff ortioides 
(Hook, f.) Oerst. Trans. Roy. Soc. N.Z. 87: 
235-241. 
— I960. Mycorrhizal infection of germi- 
nating seedlings of Nothofagus solandri var. 
cliff ortioides (Hook, f.) Poole. Pacific Sci. 
14:248-250. 
Cannon, H. G. 1941. On Chlorazol black E 
and some other new stains. J. Roy. Micro- 
scop. Soc. London 61:88-94. 
Clowes, F. A. L. 1951- The structure of mycor- 
rhizal roots of Fagus sylvatica. New Phytolo- 
gist 50: 1-16. 
1961. Apical Meristems. Blackwell Sci- 
entific Publications, Oxford. 
Darlington, C. D., and L. F. La Cour. 1947. 
The Handling of Chromosomes. Allen and 
Unwin Ltd., London. 
Johansen, D. A. 1940. Plant Microtechnique. 
McGraw-Hill Book Co., Inc., New York. 
Marengo, N. P. 1952. Formalin pyrogallol as 
a fixative for plant cytoplasm. Stain Tech. 27 : 
209 - 211 . 
Morrison, T. M. 1956. Mycorrhiza of silver 
beech. N.Z. J. Forestry 7:47-60. 
Nebel, B. R. 1940. Chlorazol black E as an aceto 
carmine auxiliary stain. Stain Tech. 15:69- 
72. 
Wigglesworth, V. B. 1952. The role of iron in 
histological staining. Quart. J. Microscop. Sci. 
93:105-118. 
