40 
Jean Dufrenoy. 
THE OCCURRENCE OF ACTINOMYCES-LIKE 
ENDOTROPHIC MYCORHIZA. 
By Jean Dufrenoy. 
(Assistant, Biological Station, Arcachon, France). 
[With Five Text Figs.]. 
I .—Mycorhiza in Adenostyles albifrons. 
1. Ecology. Small well defined patches of A. albifrons 
occur in the Beech woods of the Pyrenees, near Barbges, at 
heights of about 3700 feet. The vertical shoots bear leaves, 
heavily rusted by Uromyces cacalicc and much fed on by Chrysomela 
glortosa. Long fleshy rhizomes run horizontally, giving long 
horizontal roots, rich in trichomes for most of their length. Both 
rhizomes and roots trail in the superficial layer of undecayed, fallen 
leaves, so that the plant is very easily uprooted. 
Fig. 1. Root of Adenostyles albifrons, transverse section, stained with 
carbolic crystal violet, then treated with I + KI. m. massue, gram positive. 
n. nucleus, within a net of hyphae (not coloured) and their club-shaped 
“ massues.” J. nucleus of a non infected plamolysed cell. (Photomicr., 
oil imm. r V obj. Oc. 1., Stiassnie). 
2. The Endotroph. Many hyphae coil around the trichomes, 
and some of them push through the gelatinous pectic walls of the 
epidermal cells into the inner parenchymatous cells of the cortex, 
and even into the vascular system, the pericyclic tissues being 
heavily infected. Hyphae show nearly as well in the cortex of the 
rhizomes ; they were not observed in the petioles. 
3. Cytology of infection. Roots were fixed in Bouin’s picro- 
formol and hand-sectioned. Hyphae were directly demonstrable 
by clearing with lactophenol, or staining with cotton-blue. But it 
is best to stain with carbolic crystal-violet, then to differentiate 
with amyl-alcohol, which stains the endotroph a deep blue, while 
the host-tissues display a light metachromatic rose-colour. 
