212 
Transactions of the Royal Society of South Africa. 
It is in old plantations with fair accumulations of humus that this 
fungus occurs, and from the mycelial masses on and around roots pass 
thinner rhizomorphic strands, which, much after the nature of root hairs, 
become agglutinated to soil particles. This, combined with the fact that the 
roots suffer no injury and the presence of the fungus between the host cells, 
as reported in other cases of similar nature, is very suggestive of a mutual 
symbiotic relationship between Polysaccum and the Eucalypti. The presence 
of rhizomorphic threads intertwining between the feeding roots of the tree, 
and often connected with decaying plant remains, is also very suggestive. 
The presence of a symbiotic relationship can only be definitely estab- 
lished by properly controlled experiments with the fungus and its host 
along the lines indicated by Frank. It is hoped later to organise a set of 
experiments along these lines, and thus get more light on the subject. 
Thisleton Dyer,* in a note on the discovery of Mycorhiza, traces briefly 
the earlier literature on the subject, which, as he remarks, is a good illustra- 
tion of how accurate observations of even insignificant facts may bring one 
face to face with important and unexpected results. Lees (1841), Rylands 
(1842), Schleiden (1842), have all observed fungi in the roots of higher 
plants (mostly Neottia 7iidus avis, Rich, and Monotrojpa hypopitys), but the 
time was not yet ripe for a full appreciation of these facts, which required a 
knowledge of the theory of symbiosis. Lees and Newman, even at this 
early date, suggested that the " byssoid " fungus was essential to the 
economy of Monotropa. 
Colour in the Fungus. 
It was early observed that water extracted from the fungus a brown 
colouring matter, and though this was not particularly studied, the following 
points were incidentally noticed : 
The brown colouring matter, in addition to water, is also soluble in 
alcohol, methyl alcohol, and glycerin, but not in xylol, turpentine, ether, 
or chloroform. 
An aqueous solution is bleached by hydrogen peroxide, bleaching powder, 
and bromine water, and the colour is not restored by the subsequent addition 
of formalin. With acetic acid the solution becomes lighter in colour and 
darkens again on the subsequent addition of ammonia. Hydrochloric, 
phosphoric, nitric, tartaric, and oxalic acids give gelatinous brown preci- 
pitates, soluble in ammonia to a dark brown solution. The filtrates from 
the above precipitates are either colourless or yellowish. 
Basic lead acetate, potassium permanganate, silver nitrate, ferric 
chloride, Nessler's reagent, copper acetate, aluminium sulphate and alum 
all give gelatinous brown precipitates which with KmmO^ is very bulky. 
No change was produced by the addition of gelatine, cobalt nitrate, borax 
chromic acid, picric acid, and potassium ferrocyanide. 
* Thistleton Dyer, " Note on the Discovery of Mycorhiza," Ann. Bot., xi, p. 175. 
