of Lathrcea Squamaria, ^c. 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 (Tab. XXII. Fig. 5. a.), but after their attachment to the 

 bark they become compressed and semiglobular. On being 

 carefully remov^ed, 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. Tab. 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 ; 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 



