of Lathrea Squamaria, ác. 405 
cessary to ascertain this, as many of the tree roots are con- - 
stantly found entangled between the scales. 
- When the tubers are first formed on their fibres, they are nearly 
round (Tas. XXII. Fig. 5. a.), but after their attachment to the 
bark they become compressed and semiglobular. On being 
carefully removed, their under surface at the point of contact 
has an irregular warty appearance, arising more from the firmer 
texture of the vessels about to be described, than the almost 
gelatinous substance in which they are imbedded. These ap- 
pearances are shown in the magnified figure 5, as is also the 
surrounding lacerated cuticle, which probably excludes the at- 
mosphere in the soil from all interference with the process of un- 
natural exhaustion. Tas. XXIII. Fig. 1. & 2. represent highly 
magnified perpendicular sections of the tuber attached to the 
root of the Ash (of which latter, the portion shown is a trans- 
verse section). Fig. 2. represents it cut through longitudinally 
in the direction of its fibre: and Fig. 1. at right angles with, or 
across it. A reference to these will help the Society to under- 
stand its organization and functions. The tuber consists of a 
succulent and nearly homogeneous substance, showing only a 
cellular texture near its circumference, which gradually becomes 
more delicate interiorly, and in the central parts is entirely want- 
ing. From its under surface, or point of attachment, it sends 
down a tap or funnel-shaped process, generally straight but 
sometimes curved, which penetrates through the cortical layers 
of the root to various depths into the alburnum, but never into 
the solid woody fibre. The tap does not send out any lateral 
auxiliary branches i but a single filament or duct passes through 
it, thickening in its progress upwards ; and on its entering the 
body of the bulb dividing into several branches, each tra- 
versing its substance in a tortuous manner, and frequently 
intersecting the others, but finally approaching and unitedly 
| forming 
