Fes. 1909.] | BOTANICAL SOCIETY OF EDINBURGH 33 
or where there has been mechanical injury, one can have 
no confidence in connecting it directly with the presence 
of Heterodera. 
In one instance, however, the root had apparently reacted 
successfully against the worm. T.S. showed a triangular 
gaping wound reaching almost to the pith. In this space 
presumably the worm had been situated. Inside the thick- 
ened sheath a second, much narrower than the first, had 
formed. Opposite the wound this new sheath bent in- 
wards, traversing the inner cortex, endodermis, etc., and 
effectually cutting off the injured area. About one-third of 
the functional central cylinder was thus salved. In the 
portion cut off the cells were either lignified or filled with 
gum, while the soft tissue which had caused the gap seem 
to have been suberised. 
The nature of the tissue made no difference to its fate, 
cortex, endoderm, pericycle, phloem, and vasa were alike 
filled up. 
There are some interesting points in a comparison of the 
present attack with that noted by MM. Vuillemin and 
Legrain. The Bromeliaceze are epiphytes and xerophytes 
in tropical America. Their environment, therefore, is in 
some respects comparable to that of the plants grown at 
El Oued in the Sahara. In both cases the parasite is 
internal and causes hypertrophy of the tissues. There is, 
however, nothing in the cell proliferation noted in the 
Bromeliads analogous to the “utricles” of V. and L, 
with their multinuclear protoplasmic contents, which are 
supposed to benefit the host. So far as the Bromeliaceze 
are concerned, it is extremely unlikely that at any time 
Heterodera comes under this beneficent category. Con- 
ceivably at the first it may stimulate the root tip to greater 
activity and cause a more copious water-supply. But for 
this there is at present no evidence. Everything points 
to the association of worm and root as one of malignant 
parasitism. 
I have to thank warmly the following gentlemen :— 
Professor Bayley Balfour, who has provided every facility 
for investigating the Bromeliacez under his charge in the 
Royal Botanic Garden, Edinburgh. Mr. L. Stewart has also 
assisted in many ways. I am indebted also to the Glasgow 
TRANS. BOT. SOC. EDIN. VOL. XXIV. 3 
