ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 63 
caused by the replacement of flower-buds by branch-buds ; the branches 
are then usually short, and are arranged alternately along the stem ; the 
terminal bud is apparently neither injured nor destroyed. Palms that 
usually produce suckers at the base are rarely branched at or near the 
apex. In no instance has a branched stem been recorded in a monocarpic 
palm. 
Dimorphism of the Root-tubercles of the Pea.* — Herr B. Frank 
states that there are on the roots of Pisum sativum two different kinds 
of tubercle. The ordinary kind are small, nearly hemispherical, usually 
unbranched, and not more than from 1-2 mm. in diameter ; these are 
mostly situated on the lower part of the tap-root and on the lateral 
roots. They contain the ordinary bacteroids. In addition there occur, 
chiefly on the upper part of the tap-root, but also on the lateral roots, 
much larger much branched or lobed tubercles, united into large coral- 
like masses as much as 1 • 5 cm. in diameter. The chief distinction 
between these and the ordinary tubercles is in the nature of their 
contents, a peculiar kind of bacteroid, composed not of proteids, 
but of amylodextrin, as is shown by the greater refrangibility and by 
micro-chemical reactions. The author proposes to term the two kinds 
albuminoid- and amylo-dextrin-tubercles. While the former contain 
nearly 7 per cent., the latter contain not quite 5 per cent, of nitrogen. 
The anatomical structure and the function of the two kinds of tubercle 
appear to be identical. 
Herr H. Moeller f denies that the two kinds of tubercle, which 
occur also in Trifolium , are in any way essentially distinct from one 
another. The larger kind are simply older tubercles of the ordinary 
kind in which fatty degeneration of the proteids has taken place. He 
further states his conviction that the “ filaments ” of Frank and Praz- 
mowski are much-branched arms of an invading zooglcea of bacteria, 
which become enclosed as a foreign substance by a cellulose-membrane, 
in consequence of the irritation of the protoplasm. It is the plant that 
forms this membrane, and thus endeavours to protect itself against the 
invading parasite. 
In reply Herr Frank J points out that Muller’s objection applies not 
to Pisum , but to Trifolium , in which the two kinds of tubercle do not 
exist. He now states that the granular contents of the bacteroids which 
are stained reddish-brown by iodine are not confined, as he before 
supposed, to the tubercles of Pisum , but occur also in those of other 
Papilionaceee. In Pisum they are confined to one kind of tubercle. 
In a further communication § Herr Moeller states that he finds the 
same results with Pisum as with Trifolium. 
Structure of Lathr8ea.|| — Dr. E. Heinricher has examined several 
points in the structure of this genus, especially in L. squamaria and 
clandestina. 
The capsule of L. clandestina is a “sling-fruit,” opening with con- 
siderable force to expel the seeds, which are reduced to not more than 
four in number. The wall of the capsule is composed of two layers, one 
* Ber. Deutsch. Bot. Gesell., x. (1892) pp. 170-8 (1 p].). 
f Tom. cit., pp. 242-9. X Tom. cit., pp. 390-5. § Tom. cit., pp. 568-70. 
|| SB. K. Akad. Wiss. Wien, ei. (1892) pp. 423-77 (2 pis. and 2 figs.). 
