NOTES OX DIPTEROCAEPS. 41 



They are starchy (about 60 per cent of starch on dry weight) ; 

 but they fail as a food on account of tannins present to the 

 extent of 8 per cent. These tannins act on man as poisons caus- 

 ing indigestion, constipation and ultimately death (see Beinherz, 

 in The Agricultural Ledger, 190-i, No. 5, pp. 33—36). It is ob- 

 vious that they serve to protect the seed, but not altogether;* for 

 many animals feed on them J : and, as with all vegetation, there are 

 specialised insect-enemies. J 



The seeds of the Malayan Shoreas seem very similar in being 

 relatively rich in tannins ; and to have similar enemies. 



The parent Sal tree many attain 20 — 25 feet in girth, but it 

 is recorded that it may be a seed-bearer with as little girth as 7-J 

 inches (Troup in Forest Bulletins, New Series, No. 8, 1912). 

 Troup was unable to show any laws of variation relating to the 

 viability of seed got from trees of different sizes, of different de- 

 grees of soundness, of different localities, or of seed ripened in the 

 beginning, middle or end of the seed-time, but he suspected a 

 possible law in regard to the last, the middle of the season being 

 best. Haines (A Forest Flora of Chota Nagpur, 1910, p. 178), 

 has said that the earliest are generally bad. 



There is no albumen around the embryo plant in the seed, 

 but all its store of food is in its gorged bilobed cotyledons. It has 

 been shown for S. leprosula (this Journal, 1917, p. 161) how the 

 lobes of the cotyledons, enwrapping in their growth the placentae 

 and the sterile cells of the ovary, push themselves into the apex 

 of the fruit. In S. robusta the two lobes of the inner cotyledon 

 alone attain it, shutting out the outer, as suggested in the illustra- 

 tion above. 



The seeds, upon falling to the ground, thrust the radicle to 

 the soil chiefly by the growth of the stalks of the cotyledons, the 

 cotyledons themselves remaining loosely apposed, and scarcely func- 

 tioning as assimilatory organs. Herein is a great divergence from 

 what is to be found in those Malayan Shoreas that are known to 

 me, a divergence which carries 8. robusta to a position in the order 

 close to the genus Dipt ero car pus; for the cotyledons in Diptero- 

 carpns remain imprisoned within the wall of the fruit, do not as- 

 similate, and as the young plant grows are depleted of their food 

 through their stalks which elongate, although not exactly to plant 

 the radicle as those of 8. robusta, but accomodatingly to the elonga- 

 tion of the hypocotyl. 



* Tannins are present also in the bark of the Sal tree to the extent of 

 8 — 10 per cent (vide Pearson, Economic value of Shorea robusta, in Indian 

 Forest Memoirs, ii. part 3, 1913). 



t In Mr. Hole's experiments porcupines were troublesome {Indian Forest 

 Records, v, part 4, 1916, p. 52). 



+ E. B. Stebbing describes the Indian insect enemies of Shorea robusta 

 in a paper entitled some Assam Sal insect pests, Forest Bulletin Series, 

 1907. 



R. A. Soc, No. 79. 



