Orchid Mycorrhiza. J. Ramsbottom. 33 
volume. The nuclei become amoeboid and put out pseudopodia 
which serve to attack the hyphae. The hyphae only stain 
slightly: they increase in diameter up to about double and also 
in length. The development in some cases is so great that the 
cell is quite filled with the thick mycelial mass and the nucleus 
is crumpled by the hyphae. Enclosed by the pseudopodia the 
latter gradually lose their outline until frequently they cannot 
be distinguished from protoplasmic trabeculae. The victorious 
nucleus then assumes a round form and normal volume and re- 
constitutes its chromatin network. The endophyte is reduced 
to an amorphous yellowish clump with indistinct contour, and 
is absolutely devoid of life: it is surrounded by a cellulose 
membrane. It would seem that as the root ages the clumps 
finally disappear. After the formation of the clump starch often 
reappears in the cell. Burgeff states that the fungus in the host 
cells can re-attack digesting cells when similar stages are again 
gone through. We shall return to the question of digestion 
when we consider the seedling. 
GERMINATION OF SEEDS. 
The difficulty in germinating the seeds of orchids is one which 
has been known for a considerable number of years. In fact, 
it was not until 1804 that any orchid seedlings were described, 
when R. A. Salisbury figured those of Ovchis Morio and Limo- 
dorum verecundum. Later, many botanists suchas Link, Irmisch, 
Beer, etc., added to our information concerning the stages of 
development. Orchid growers evolved the method of sowing 
seeds on the soil containing the parent plant*, and it was in this 
manner, or some modification of it, that most of the hybrids 
known in horticulture were raised. The facts known, i.e., the 
difficulty in germinating seeds unless placed on orchid soil and 
the presence of fungi in the roots, led many to suspect that the 
fungus was concerned in some way with the success or failure 
of germination. 
We have mentioned that when Reissek recognised the fungal 
nature of the cell inclusions, he attempted to isolate them. This 
attempt, long before the days of bacteriological technique, was 
bound to end in failure and the fungus he isolated was a species 
of Fusarium, a genus which has been time and again proclaimed 
as the consort of the orchid root. (The genus Nectria also has 
often been assumed to be the endophyte.) It is to Noél Bernard 
that we are indebted for our chief knowledge of the facts of 
orchid germination. This brilliant young French investigator 
began his studies on mycorrhiza in 1899, and they extended until 
his death in 1911. His first investigation was on the germina- 
* I believe Dominy of Messrs Veitch and Sons introduced this practice. 
M.S. 3 
