626 BOWMAN— ECOLOGY AND 



between fertilization and the fall of the seedlings of the species in 

 the former region and states it to be nine or ten months. 



Before leaving this subject of morphology and histology, there 

 are two anatomical features which deserve special mention and 

 which occur in nearly every tissue of Rhizophora. These two 

 peculiarities are the indioblasts or trichoblasts and the tannin cells. 

 The trichoblasts were, according to Warming, perhaps first de- 

 scribed by Decaisne,-''' who remarked their presence in a " root." 

 They are perhaps better seen, however, in a hypocotyl, which if 

 broken transversely the surface of the fracture is seen to be densely 

 bristled with the tips of the thousands of idioblasts embedded in 

 the intercellular spaces of the cortex, as well as the medulla and 

 even vascular region (Fig. 2, PI. V.). The most of the idioblasts 

 in this organ, as well as those in stem and roots, are composed of 

 four elongated and taper pointed branches joined in the middle by 

 a short connection, the whole structure appearing as a letter H (Fig. 

 2, PI. IV.). The idioblasts of the leaves, however, are more irregu- 

 lar and branched or even stellate in form with the branches rami- 

 fying among the cells. Sections of this type are seen in Fig. i, 

 PI. V. In the older and more lignified tissues, as the stem and also 

 in the hard calyx and ovary, the idioblasts more nearly resemble the 

 stone cells of fruit pits and of the leaves of Camellia a.nd Osmanthus, 

 having the lumen almost entirely filled up. These structures, as 

 Warming remarks, very soon render a razor entirely unfit for use 

 in the preparation of histological material. The same author re- 

 gards the function of the structures as mechanical in preventing 

 shrinking and shriveling of tissues when exposed to the great heat 

 of the sun. But as they are frequent also in parts which are not so 

 exposed, as for instance the absorptive roots and the interior of the 

 fruit and flower, etc., this theory of support against shrinkage due 

 to heat is not necessarily true, but it may be conceded that their role 

 is mechanical and they do support the large intercellular spaces found 

 in some of the tissues. In discussing fibers and hairs, De Bary"^ 

 says : " There occur in phanerogams fibers which are freely and 



98 Decaisne, J., Annales dcs Sciences Naturclles, 2, Series 4, p. 76, 1835. 

 9^ De Bary, A., " A Comparative Anatomy of tlie Vegetative Organs of 

 the Plianerogams and Ferns," tr. Bower and Scott, pp. 130 and 220, 1884. 



