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The Anatomy of the Mummy Pea. 
In some species (e.g., T. anrea) the apical cap may become 
cumbrous and act rather as an impediment to growth than other¬ 
wise, in which case it is frequently displaced by a slight change in 
the direction of growth of the apical cell, and a new cap developed. 
Botanical Laboratory, 
Birmingham University. 
THE ANATOMY OF THE MUMMY PEA. 
By R. H. Compton. 
| With Four Figures in the Text.] 
\HE Mummy Pea is a striking variety of Pisnm sativum 
characterised by the production, in the upper part of the 
plant, of a greatly dilated axis bearing a dense cluster of leaves and 
short inflorescences arranged promiscuously.' The broadening 
begins to take place about a foot above the ground, and the plant 
produces no long lateral branches. The whole appearance is 
abnormal, and is evidently the result of a fasciation. As will be 
shewn in the sequel the structure is that of the very rare condition 
known as ring-fasciation. The Mummy Pea breeds perfectly true, 
and its peculiar character behaves as a simple recessive in crosses 
with the normal type. 2 Owing to the distinct appearance and its 
power of breeding true it has sometimes been considered as a 
distinct species, P. umbellatum , Miller. 
A closer inspection shews that the distended part of the main 
axis is funnel-shaped: its tip is open, and a probe can be passed 
through the aperture into the body of the plant. Thus the whole 
of the cavity of the dilated stem is open to the external air, insects 
and debris being able to enter freely. 
An investigation of the anatomy of the axis reveals a very 
curious condition. The lowest internodes exhibit the normal 
1 A photograph is given by A. D. Darbishire ; “ Breeding and the 
Mendelian Discovery,” 1911, Fig. 8. 
2 G. J. Mendel. Verh. naturf. Ver. in Briinn, Abh. IV., 1865 
(Engl. Transl. by W. Bateson, “Mendel’s Principles, etc,” 
1909, p. 317). 
