EMBRYO, SEED AND CARPEL IN THE DATE. 117 







ling as an excrete, and the evidence supports his view. Con- 

 trariwise, Servettaz (1909) has observed that tannin occurs 

 in certain situations in the young, rapidly developing ovule 

 (in the Eleagnaceae) and argues, with equal right, that here 

 this substance is concerned with nutrition. In view of these 

 observations, it would seem the rational procedure to regard 

 the tannin w T hich accumulates, and remains permanently, in 

 certain cells of the germinating date as different chemically 

 from that in the young ovule of the Eleagnaceae. The 

 chemist may tell us later that, indeed, the former is tannin, 

 and the latter not. These two instances only are cited, 

 because as w r e shall presently see, they are pertinent to the 

 matter in hand. For the present purpose, we must be con- 

 tent to call those substances tannins which afford us the 

 visible reactions which are usually resorted to, and rely upon 

 observation to tell us whether a particular tannin is an excrete 

 or a nutrient. 



Aplastic tannin is known to occur in the date. Thorn- 

 ber 9 studied a Series of date fruits from the "size of a pea 

 until full ripeness" and came to the conclusion that there is 

 "no general distribution of tannin" but that it is "strongly 

 segregated in a layer of very large cells near the surface of 

 the fruit and, especially in the younger stages, near the 



seed." Avoiding hypercriticism as to the meaning of "near 

 the seed" these facts have been further mentioned and illus- 

 trated by Vinson (1910) for the purpose of demonstrating 

 the value of ethyl nitrite vapor in the study of tannin in 

 plant tissues. Vinson believes that "a green date may also 

 be easily divided into astringent and non-astringent portions 

 with a pocket knife" and has said to me personally that, 

 before ripening, the portion (mesocarp) lying beneath the 

 layer of idioplasts (f. 32) is not astringent, but that the 

 contents of the idioplasts may be expelled by gentle crush- 



■ 



ing and appear mucilaginous. The inference is at hand 

 that the tannin is confined wholly to the idioplasts, but, for 

 reasons which will be given beyond, I think this is not quite 



9 1906. Not over his personal signature. 



% 



