6 o8 
Notes. 
and deeply pitted, and they are gradually transformed into characteristic sclerenchy- 
matous fibres (Fig. 4). The epidermal fibres are elliptical in transverse section ; 
their lumina are larger than in the underlying layers, and their walls much thicker. 
B. The outer integument. 
Immediately after pollination, this integument begins to increase in thickness, 
until it attains to the relatively considerable size shown in Figs. 1 and 4. This 
increase is due to the appearance of bands of meristem, running down the integument 
Figs. 1-4. Sections through the seed and ovule of C. papaya, to show the structure and develop¬ 
ment of the seed-coat. Lettering in each figure : 
T T . , ( a = inner epidermis 
Inner Integument \ , . 1 
( 0 = outer L 
= endotesta. 
Outer Integument j C ,~ * m l er ” ) 
^ ( a = outer „ = sarcotesta. 
e = ridges of the endotesta. 
A B 
IlG. i, A and B. Median longitudinal and transverse 
sections of the mature seed, x 3. 
Fig. 2. Transverse section through in¬ 
teguments and nucellus of ovule before 
pollination. X120. 
Fig. 3. The same, a short time after pollination, showing a developing ridge of the 
endotesta on each side of the section, x 120. 
in the layer immediately underlying the outer epidermis, and marking the future 
position of the ridges of the endotesta. By the divisions of these meristems, a ridge 
gradually arises along each band. These ridges, like the meristems, generally run 
roughly parallel in a longitudinal direction, but are often quite irregular. Two 
of these developing ridges are shown in transverse section in Fig. 3, and it will be 
noted that at the base of the depression between them, six or seven adjacent cells of 
the hypodermal layer have remained undivided, merely increasing in size. A similar 
row of about six hypodermal cells is found in transverse section at the base of each 
depression between the ridges, and these cells never divide, but continue to increase 
