APPENDIX 575 



occurred to me that this seed-structure might be the result of a lost vivi- 

 parous habit. One apparently had to deal here not with an ordinary seed 

 containing an embryo in the midst of albumen, but with a seed in an 

 arrested stage of germination surrounded by a body that might perhaps 

 prove homologous with the " cotyledonary body " of Rhizophora. The 

 process of development that goes on without a break in Rhizophora, from 

 the fertilisation of the ovule to the detachment of the seedling from the 

 branch, was here, as I considered, arrested after germination had begun, 

 but before the protrusion of the seedling from the fruit. With nearly all 

 plants, as I reflected, there is a rest-stage of varying length, which might be 

 called the seed-stage. With the mangrove-genera, Rhizophora and Bruguiera, 

 I had convinced myself by a long series of observations, the results of which 

 are given in Chapter XXX., that this rest-stage does not exist. It occurs, 

 I argued, in Barringtonia, but only after germination has begun, and, there- 

 fore, displaced when compared with the typical seed-stage of most plants. 



In this connection it may be noted that a difference in germinating 

 behaviour might be expected between the two shore species on account of 

 their difference in stations, Barringtonia speciosa growing on the sandy 

 beach, and B. racemosa in the wet ground around a mangrove-swamp. 

 There is a strong suspicion that the rest-stage in B. racemosa is very short, 

 though I never found germination in progress on a tree (see Note 37). 

 There is no doubt, on the other hand, that the rest-stage of B. speciosa is 

 often, as with most other plants, very long. This, then, was my lesson 

 from the Barringtonia fruits on the banks of the Rewa, and the question 

 arose whether this interpretation of these curious seed-structures accorded 

 with the opinion formed of their nature by botanists. 



Curious seed-structures of this kind must have their significance in the 

 history of the plant ; and on returning to England I looked a little further 

 into the matter. To follow up this kind of inquiry, however, would carry 

 me far beyond the limits prescribed for this note, and I have only treated 

 it here in a tentative fashion. Different botanists of eminence have paid 

 attention to this subject, amongst them Roxburgh, Thomson, and Miers 

 (see Dr. T. Thomson in Journ. Linn. Soc. Bot., vol. ii., p. 47, 1858, and 

 Mr. J. Miers in Trans. Linn. Soc. Bot., vol. i., 1880). It would appear 

 that the seed-structure of Barringtonia is also found in Careya, a genus of 

 the same Myrtaceous tribe, and in Garcinia and other genera of the 

 Guttiferae, as well as in other inland plants. 



Mr. Miers, after reviewing the opinions of his predecessors, gives the 

 results of his own investigations. The solid embryo found in Barringtonia 

 and many other genera consists, he observes, {a) of an external portion, 

 the " exorhiza," which nourishes the germinating seed and then dies away ; 

 (b) of an internal portion, the "neorhiza," which, growing at each end, 

 forms the central portion of the stem and root ; and (f) the " medullary 

 sheath " of Mirbel, that lies between the two, and is composed of elemen- 

 tary vascular tissue, which ultimately gives origin to the wood, bark, and 



