386 Boodle . — On some points in the 
tions of Welwitsch and Prantl 1 to be correct, it produces no 
adventitious buds but has monarch roots. Such cases might 
arise in the event of a species giving up the production of buds 
but retaining monarch structure. 
O. ellipticum is another exception as it produces adventitious 
buds, but has not monarch roots, according to Poirault. How- 
ever, one cannot really test the probability of the theory 
without knowing the number of buds produced in proportion 
to leaf-area, &c. 
O. Bergianum has a small leaf-area, and produces adventi- 
tious buds 2 , and has both diarch and monarch roots 3 . It 
would be interesting to know whether the monarch roots are 
those that produce the buds. 
2. Secondary Thickening. 
In sections of mature roots of Ophioglossum vulgatuni one 
sometimes finds developing tracheides at the periphery of the 
xylem-mass. By staining transverse and longitudinal sections 
with methyl-green and eosin this is clearly shown. If the 
double staining is carried out so as to give the right balance 
to the two colours, the mature xylem is bright blue (or bluish 
green) and the phloem and parenchyma are pink ; while 
any half-lignified tracheides present take up both stains and 
become purple, so that they are made very conspicuous 4 . 
Fig. 9 is a transverse section of a root in which are five 
developing tracheides (/). Fig. 10 is more highly magnified, 
and shows one developing tracheide (/) with its protoplasmic 
contents. Fig. 1 1 is a longitudinal section showing part of 
the xylem with one developing tracheide on the left, contain- 
ing protoplasm and nucleus («). In the preparation from 
1 Prantl, l.'c. 
2 Poirault, Journal de Botanique, vi, p. 73. 
3 Bower, 1. c. 
4 The stain used was watery solution of methyl-green, followed by alcoholic 
solution of eosin. It unfortunately fades. 
