353 
• and its Mycorhiza . 
powers of the nucleus of the cell 1 , there is an increase in the 
metabolic activity of that cell Secondly, there is a sudden 
rise in the assimilation of nitrogen which exhibits itself in the 
rapid synthesis of proteids. Thirdly, the carbohydrate manu- 
factured by the host is concerned in the formation of proteid 
in the mycelium. 
After a time the protoplasm of the hypertrophied bladder 
in the mediocortex diminishes in amount ; and, pari passu , 
there is a deposition in the bladder of a yellow mass with 
rod-like bodies. This yellow mass with the bodies is 
absolutely useless to the host ; for, as the mycorhiza decays, 
these masses remain unaltered though the protoplasm of 
the dying host-cells is conducted away, and at the exposed 
and disintegrated surface of the decayed mediocortex the 
yellow masses may be recognized. Hence the protoplasm 
of the hyphae in the mediocortex is partially broken down 
into resistent excreta absolutely useless to Thismia. As 
the protoplasm of the bladder is vanishing and the yellow 
mass appearing, the bladder shrinks and its wall collapses. 
A liquid therefore leaves the bladder. Now evidence has 
been given earlier in this paper that the liquid is not con- 
ducted away along the slender portions of the hyphae, 
because they die soon and are occluded, and because they 
always are slender in calibre. Hence it must be concluded 
that the moribund mycelium pours a liquid into the host-cell . 
As to the nature of this liquid one cannot do more than 
guess. 
Thus it is established that in the mediocortex of Thismia 
there is an interchange of material between Fungus and host, 
and that that material is manufactured by the two symbionts 
respectively. In the Orchidaceae, in Paris , Marattiaceae, &c., 
doubtless there is likewise an absorption on the part of the 
hyphae of substance manufactured by the host ; for there 
are indications of the effect of the nucleus of the cell on the 
1 Compare the researches of animal physiologists in showing that the size and 
staining power of a nucleus is a good index of the metabolic activity of that cell 
(Heidenhain on secretory cells, Hodge and G. Mann on nerve-cells). 
