378 
L. H. MACDANIELS 
Pyrus Mains 
Fig. 26. Radial section showing sieve plates upon radial walls of sieve tubes. 
X 450. 
Fig. 27. Same, tangential section showing sieve plates in section. In this 
species there is apparently no differentiation of side and end walls. X 270. 
Prunus Persica 
Fig. 28. Mature stem, tangential section showing single transverse oblique 
sieve plates. X 450. 
Ailanthus glandulosa 
Fig. 29. Mature stem, transverse section showing single transverse sieve 
plates in face view. X 450. 
Rohinia Pseudo-A cacia 
Fig. 30. Mature stem, radial section showing transverse sieve plates, slime 
globules and probable companion cells. X 270. 
Fig. 31. Resting cambium of mature stem, tangential section. X 100. 
Fig. 32. Tangential section of phloem near the cambium showing development 
of cambium cells into parenchyma and sieve tubes. X 100. 
Fig. 33. Cambium of four-year stem, tangential section showing smaller size 
of cambium cells as compared with the mature (fig. 31). X 100. 
Fig. 34. Phloem near cambium of four-year stem, tangential section. X 100. 
Fig. 35. Transverse section, two-year root. Note small number and size of 
sieve tubes as compared with mature (fig. 36). X 270. 
Rohinia Pseudo- Acacia 
Fig. 36. Mature, growing stem, transverse section. X 270. 
Cornus paniculata 
Fig. 37. Transverse section showing sieve-like pitting in end walls of paren- 
chyma. X 450- 
Fig. 38. Radial section showing sieve-like pitting on radial walls. X 450. 
Tilia americana 
Fig. 39. Transverse section, mature stem. Note two types of parenchyma. 
X 100. 
Cephalanthus occidentalis 
Fig. 40. Transverse section, mature stem. X 100. 
Sambucus canadensis 
Fig. 41. Transverse section, one-year root. X 270, 
Fig. 42. Transverse section, three-year root. X 270. 
Fig. 43. Transverse section, mature stem. X 270. 
Fig. 44. Tangential section showing sie\e piates in section upon oblique end 
walls. X 270. 
