Sieve-Tubes of Times. 6 1 1 
Fig. 22. An old sieve-plate with a much-swollen callus-cushion ; the callus-rods 
are seen in the pit-closing membrane. ( x 750.) 
Fig. 23. A pit between a sieve-tube and an albuminous cell showing callus 
formed on the sieve-tube side only, and reaching to the lamella. Cf. PI. XXXI, 
Fig. 12. (x 750.) 
Fig. 24. Sieve-plates in radial sections of the phloem, showing sieve-fields 
in surface-view. 
Fig. 25. Transverse section of the phloem, showing an anomalous formation 
of callus ( k .) owing to the alteration of the cellulose layers of part of the tangential 
and radial walls of two contiguous sieve-tubes. At (A) a mature sieve-plate 
is seen, and at (mr.) a medullary ray with threads in a tangential wall. 
Fig. 26. A medullary ray cell stained with safranin and water-blue, showing 
starch-grains giving the callus reaction. 
Fig. 27. An older cell of the same ray, showing a formation of callus ( k .) against 
the tangential wall on the side towards the cortex. ( x 75°*) 
