26 TRANSACTIONS OF THE [ Sess. Lxxm0.. 
of sclerenchyma, outwardly they are bounded by much 
weaker tissues—protoxylem, soft phloem, and wood par- 
enchyma. The walls thus unequally supported must be 
better able to resist distortion, owing to the presence at 
intervals of these strengthening bars. 
Good preparations of these septa can be obtained by 
immersing the sections for twenty-four hours in aniline- 
water-safranin, washing out with weak acid alcohol, and 
then counterstaining with aqueous methyl blue. If the 
washing out is checked at the right moment, the red and 
blue of the bars and septum respectively are pure and 
their contrast decided. 
MorRPHOLOGICAL CHANGES INDUCED IN Roots oF BromME- 
LIACEZ BY ATTACK OF HETERODERA sp. By Rev. 
James Warterston, B.D., B.Sc. (Plates IV., V.) 
The object of this communication—which cannot claim 
to be more than a preliminary notice—is to give a short 
account of changes induced in the various root tissues of 
the Bromeliacez by the presence there of a species of 
Heterodera. A more thorough examination has been made 
of the parasite’s ravages in Pitcairnia and Billbergia, but, 
while the following observations were made on species of 
these genera, the attack is not confined to them. 
Heterodera is a genus of the Tylenchide, a family of 
Nematode worms. Tylenchi, the stem-eel worms, are only 
too well known to agriculturists in Britain and elsewhere 
from their devastation of cereals. Heterodera, first recog- 
nised in the early sixties, shares this evil family reputation. 
Ai. schachtii, Schmdt., e.g. causes “ beet-sickness,” sometimes 
so severe that one-third of the crop (5) is destroyed. Like 
Tylenchus it attacks wheat (2), barley, ete. Cabbage (3) 
has also been injured. H. radicicola (4) was found in the 
Sahara to invade carrots, turnips, beets, tomatoes, the egg- 
plant (Solanum Melongena), onions, and celery. . 
It would be out of place to describe in detail the 
anatomy, etc., of Heterodera. But one or two pomts in 
its structure and life-history may be mentioned for an 
understanding of its characteristic attack. 
