OF THE EASTERN UNITED STATES 355 



pitted. Solereder errs in stating that the maximum diameter of the 

 vessels varies between .02 and .05 mm. (9) In this root, the writer has 

 found it to be .096 mm. The woody fibres are extremely elongated and 

 taper-ended. Their walls are considerably thickened with deposits of 

 hgnin and show oblique pores. The wood parenchyma cells are relative- 

 ly few and contain starch and frequently monoclinic prisms of calcium 

 oxalate. The primary medullary rays are mostly 1-4 cells, rarely 

 1-5 cells, broad. The secondary medullary rays are 1-2 cells broad. 



Myrica Carolinensis, Miller. (Plate 86. Fig. 14.) 



The root of M. Carolinensis resembles that of M. cerifera in respect 

 to tissue arrangement, character of cork, cells containing " lignine-gom- 

 meuse" and tracheae, some of which contain Actinomyces. It differs 

 from M. cerifera root in the following particulars: The cortex shows 

 larger intercellular air-spaces with more crystals of calcium oxalate. 



The sclerenchyme elements are more numerous and usually in 

 groups of several, forming small islets. 



The phloem contains fewer bast fibres and for the most part broader 

 medullary rays. Many of the latter are 1-5 or 1-6 rows of cells in width. 



The tracheae are less numerous while the woody fibres are more abun- 

 dant. The tracheae are to some extent narrower and show both pitted 

 and reticulate markings on their walls. 



The primary medullary-rays are wider and more numerous. They 

 range from 1-5 to 1-6 rows of cells broad. The cells of both the primary 

 and secondary medullary rays are somewhat broader and shorter. 



Myrica Macfarlanei, Youngken. {M. cerifera x M. Carolinensis) 



The root of this hybrid between M. cerifera and M. Carolinensis 

 shows characters some of which resemble both parents, some, one parent 

 and others which are peculiar to itself. 



It resembles both parents in respect to its cork, its cells containing 

 gummy lignin, Actinomyces in ducts, barred septa, and crystal fibres 

 accompanying the hard bast. 



It resembles M. Carolinensis in the number of primary medullary-rays 

 and in having comparatively broad medullary-ray cells. 



It differs from both parents by having larger intercellular air spaces 

 in the cortex, more crystals of calcium oxalate in both the cortex and 

 phloem, broader and more numerous sclerenchyme elements in the cortex, 

 and narrower tracheae. (Plate 86. Fig. 15.) 



The primary medullary-rays are 1-6, occasionally 1-7 rows of cells 

 in width. 



