BOTANICAL GAZETTE. 1 85 



come both the soft and the hard tissues. In the case of the pear 

 there are manifest reasons for supposing the sclerenchyma to be a 

 legacy from the period when pears as fruit were far less luscious 

 than now. They are found in the pear stem as well as in the fruit. 

 In the fully formed Sphagnum moss we recognize cells of two dis- 

 tinct characters; the one large, colorless, and with plain communi- 

 cation between the adjacent cells; the other small, having chloro- 

 phyll and destitute of communications; yet, if we may credit Hux- 

 ley, both of these kinds are very similar in their early growth. 



To return to the Eriodictyon, the character of the tissues 

 have appeared to me to indicate how widely ultimate cell 

 forms may depart from the original source out of which they all 

 have sprung, and at the same time to show connecting links be- 

 tween even the most divergent members. In fact I am tempted to 

 regard the whole plant as a forcible illustration of the doctrine of 

 evolution. 



Commence for example with figure 1, where we have the 

 typical large, thin-walled, porous pith-cell, found in the very center 

 of the stem. Outside of this, but still in the pith, are other small 

 er, thicker-walled cells, figure 2, which when observed on trans- - 

 verse section are roundish, but seen on longitudinal section are 

 quite distinctly rectangular. More remote from the center of the 

 pith, yet in it, we find the cells represented in figure 3; and this 

 form is a direct transition to figure 1, which is taken from the 

 medullary ray. Here then the transition, not by isolated cells, but 

 by groups ot cells, from one extreme of fundamental tissue to the 

 other appears regular and gradual and ends in cells with well-marked 

 sclerenchymatous character. 



Suppose now we take the types of distinctly prosenchymatous 

 character, which the bast zone ot Eriodictyon furnishes. Figure S 

 is the more usual form of bast found in other plants, though occa- 

 sionally seen in Eriodictyon. Figure 7 will give us one of the 

 commonest shapes of bast in Eriodictyon-, and figure 6 represents a 

 snorter kind often discovered in the ' bast and also throughout the 

 woody part of the stem. Figure 5 may be called a representative 

 sclerenchymatous cell, though it is found also in the bast zone. 

 Here again we have four forms of cells which represent the trans- 

 ition from bast to sclerenchyma, and all in the same belt of the 

 same plant. 



The structure ot the leaf of Eriodictyon glutirioswm is even 

 more suggestive. Figure 11 is a section through such a leaf. The 

 first striking peculiarity is the thickness of the epidermal cells as 

 shown by a and by ./'. This is particularly marked in a, the upper 

 surface, where not only the thick walls of the cells but the pores in 

 them remind one of figure 3, taken from the outer pith. This as be- 

 ing the more exposed surface would naturally show the denser 

 tissue. The secreting gland, b, has no particular import in the 

 present connection. Three rows (ordinar\\y) of palisade cells come 



