276 Scott and Brebner . — On the Anatomy 
much to be learnt, even from the best investigated cases. The 
state of our knowledge regarding those very numerous modes 
of secondary growth which are usually classed as ‘anomalous’ 
is much less satisfactory. Here as elsewhere the rule holds 
good that structure cannot be understood without develop- 
ment, and we still know but little of the development in a 
large proportion of these cases. It is the object of the present 
paper to clear up, as regards one anomalous genus, some of 
the points which previous investigations have left obscure. 
Literature of the Subject. 
The original literature relating to the anatomy of Strychnos 
is very meagre, and so far as we are aware, is the work of 
three investigators only. The peculiar structure of the stem 
appears to have been first noticed by Fritz Miiller 1 . He 
found that the wood is traversed by a number of isolated 
strands of soft tissue, but he was not in a position to make 
any microscopic observations, and so the exact nature of this 
tissue could not be ascertained. The first to make any de- 
tailed investigation of the subject was de Bary 2 , and his 
account is still the one generally accepted. His work is so 
familiar to English readers that it is unnecessary to do more 
than give the briefest possible summary. De Bary found that 
in the stem there is at first a normal ring of bicollateral leaf- 
trace bundles. The external primary phloem consists of 
small groups of cells, among which sieve-tubes could not be 
demonstrated with certainty. The cambium appears in the 
normal position, but forms no sieve-tubes in the secondary 
bast. Its activity is for a time almost entirely centrifugal, 
producing secondary wood only. At a later stage consider- 
able additions are made to the external bast, but only in the 
form of phloem parenchyma, and, in some species, of short- 
celled sclerenchyma. The secondary sieve-tubes are situated 
1 Uber das Holz einiger um Desterro wachsenden Kletterpflanzen, in Bot. 
Zeitung, 1866, p. 68, Fig. 10. 
2 Vergleichende Anatomie d. Vegetationsorgane, 1877- Eng. ed. 1884, pp. 
578-580. 
