July, 192..] 
. THE ORCHID RE VIE W. 
ORCHID FUNGUS. 
71 SUBJECT of considerable importance to Orchid growers was the 
.O highly interesting exhibit by Messrs. .Gharlesworth &~Co., dt.the 
recent Chelsea Show, of their Pure Culture System of raising Orchids. 
Probably no seeds present greater difficulties in the matter of germination 
than those of Orchids, and, although it has long been known that the best 
results are obtained when the seed is sown on the surface of the compost 
surrounding the' parent plant, it was Bernard who first published the 
^explanation. 
Orchid seeds that are supplied only with moisture merely swell into little 
.green globules as the result of osmotic action, and eventually die through 
apparent lack of sufficient nutriment. But if the seeds be supplied with the 
necessary fungus they develop normally and ultimately become organisms 
-capable of leading an independent existence. Not so long ago it was 
thought that the entry of the fungus into the seed had little more than an 
oxciting influence, much in the sense that touching the pendulum of a clock 
sets the mechanism therein in motion. But more recent investigation 
suggests that the fungus contributes, possibly in a symbiotic manner, to the 
food supply of the embryonic seedling. In support of this latter suggestion 
it has been found that soon after the minute hairs make their appearance 
on the roots, disorganisation of the fungus takes place in the cellular tissue 
of the seedling. In other words, as the young seedling progresses, the 
necessary nutriment is obtained through the collecting influence of the 
newly-formed root hairs, instead of by fungal infection of the corm. 
The late Mr. Charlesworth was a keen investigator in this matter, and 
some of his microtome sections were on view in the Scientific Department 
•of the Chelsea Show. Considerably enlarged photographs prepared from 
these sections included: (1) Tranverse section of the root of a British 
species of Habenaria, about £ inch from the tip, with the fungus in 
the cortical cells. (2) Longitudinal section of Habenaria, showing the 
fengus in the cortical cells. (3) Fungus taken from root. (4) Same more 
highly magnified. (5) Whole seed of Cymbidium. The seeds are very 
small and are produced in enormous numbers, 850,000 were estimated in a 
single capsule of C. Tracyanum. (6) Section of seed of Cymbidium 
showing the little differentiation present—merely a slight difference in the 
size of the constituent cells. The seed of an Orchid does not contain an 
embryonic plant such as is almost universal in flowering plants. Further 
photographs showed that the fungus enters the larger cells, whereas the 
growing points become laid down at the opposite pole. (7) Seed of 
Odontoglossum sown seven days, stained and mounted whole. The 
mycelium of the fungus could be seen passing through the meshes of the 
