496 
Herpes tonsurans. Same as ring-worm. 
Heteroecious. Same as metoecious. 
Heteromerous. In Lichens: a thallus 
with stratified tissue owing to algal cells 
forming an algal layer and dividing the 
hyphal tissue into an outer (rind) and an 
inner (medullary) stratum is termed 
heteromerous. Comp. homoiomerous. 
Heterosporous. Having asexually pro- 
duced spores of more than one kind. 
Comp. homosporous. 
Homoiomerous. In Lichens: a thallus 
with algal cells and hyphae distributed 
uniformly and in about equal proportion 
is termed homoiomerous. Comp. heter- 
omerous. 
Homologous. Having the same position 
and development. 
Homosporous. Having asexually pro- 
duced spores of only one kind. Same as 
isosporous. Comp. heterosporous. 
Hydrotropism. Phenomena induced in 
a growing organ by the influence of 
moisture. 
Hymenial Alga. In Lichens: algal cell 
in a sporocarp. Same as hymenial 
gonidium, 
Hymenial gonidium. Same as hymenial 
Alga. 
Hymenial layer. Same as hymenium. 
Hymenium, Aggregation of spore-mother- 
cells, with or without sterile cells, in a 
continuous stratum or layer upon a sporo- 
phore. Same as sporogenous layer, 
hymeniallayer. Seealso discus,lamina 
proligera, lamina sporigera. 
Hymenophorum. Portion of a sporo- 
phore which bears a hymenium. 
Hypha. The element of a thallus in 
most Fungi; a cylindric thread-like 
branched body consisting of a membrane 
enclosing protoplasm, developing by apical 
growth and usually becoming transversely 
septate as it developes, 
Hyponasty. That state of a growing 
dorsiventral organ in which the ventral 
surface grows more actively than the 
dorsal surface. Comp. epinasty. 
Hypophloeodic. Of Lichens: living in the 
peridermofaplant. Comp. epiphloeodic. 
Hypothallus. In crustaceous Lichens: 
marginal outgrowth of hyphae, often 
strand-like, from the thallus. Same as 
protothallus. 
Hypothecium. Layer of hyphal tissue 
immediately beneath a hymenium. Same 
as subhymenial layer. 
Inception (Anlegung). First beginning. 
Inner peridium. See peridium inter- 
num. 
Intracellular. Inside a cell. Comp. extra- 
cellular. 

EXPLANATION OF TERMS. 
Interweaving (Verflechtung) of hyphae. 
Union by interwining without firm cohe- 
sion with one another. 
Intralamellartissue. In Hymenomycetes: 
same as trama, 
Intramatrical. Inside a matrix or nidus. 
Comp. extramatrical. 
Involucrum. Persoon’s term for velum. 
Involution-form. Swollen bladderlike 
form of Schizomycete, supposed to be 
a diseased condition of the form with 
which it is found associated. 
Involution-period. Same as resting 
period. 
Involution-stage. Sameas resting stage. 
Isogamy. Conjugation of two gametes 
of similar form. Comp. oogamy. 
Isosporous. Same as homosporous. 
Kernel. In. Pyrenomycetes: old term 
for the whole of the softer part of the 
pyrenocarp within the firm outer wall. 
Also termed nucleus. 
Lamella. In Hymenomycetes: vertical 
radial plate on the under surface of the 
pileus upon which the hymenium is 
extended. Same as gill. 
Lamina proligera. Same as discus. 
Lamina sporigera. Same as discus. 
Lipoxenous. A parasite that leaves its 
host and completes its development inde- 
pendently, and at the expense of reserve 
of food appropriated from the host is 
lipoxenous. Comp. metoecious. 
Lipoxeny. Desertion of a host. 
Lysigenetic. Formed by disorganisation 
or dissolving of cells. 
Macrogonidium. Large gonidium com- 
pared with others produced by the same 
species. Same as megalogonidium. 
Comp. microgonidium. 
Madura. Disease in man characterised 
by swelling and degeneration in feet and 
hands and supposed to be due to 
Chionyphe Carteri, Berkl, but the 
causal connection is not definitely made 
out. 
Malignant oedema. Disease in animals 
like anthrax and due to a Bacillus in 
form resembling Bacillus Anthracis. 
Marginal veil. In Hymenomycetes: a 
membrane stretching from the margin of 
the pileus to the surface of the stipe in 
the young sporophore and covering over 
the hymenium. Same as velum partiale. 
See velum. 
Medulla. Central tissue within the rind 
of a Fungus-body. In Lichens: same 
as stratum medullare. 
Megalogonidium. Same as macrogo- 
nidium, 
