108 MR. MIERS ON SEVERAL INSTANCES OF ANOMALOUS DEVELOPMENT 



narrow basal extremity, wliicli is enclosed in a short fleshy sheath, part of the funicle, from 

 which it has broken away, and by which it is comiected with the placenta, and suspended 

 in the pulp of the fruit : a groove runs parallel with the margin on each face close to the 

 periphery, forming in this manner a prominent zone aU round the edge of the seed, which 

 is broader towards the base, and which thus forms a short auricular expansion on each 

 side of the hilum. On a former occasion (p. 92) I described the outer crustaceous 

 tunic, hitherto considered as the testa, but which I shall prove to be of the nature of an 

 aril, formed subsequently to the fertilization of the ovule, around its original integu- 

 ments : it was there shown to be formed of three series of deposits, the epiderm, meso- 

 denn and endoderm : the epiderm is a thin delicate membrane that covers the whole of 

 the seed, and is extended beyond the hilum in the manner above-mentioned, as an exten- 

 sion of the sheath of the umbilical cord ; the fleshy mesoderm has been before described, 

 its numerous branching fibres being emanations from the bundle of simple vessels that 

 fill the sheath of the funicular cord, and that surround the thread of spiral vessels pro- 

 ceeding from the placenta, that terminates in the raphe of the seed ; the principal portion 

 of the tunic is the endoderm, which is, in fact, a crustaceous compressed sac, enclosed in 

 the above-mentioned vesicular terminal enlargement of the sheath of the umbilical cord ; 

 it forms a casing closed all round the seed, except at the hilum, where it has a long open 

 slit, within the mouth of which is a considerable open space filled with pithy loose cel- 

 lular tissue, wliich fills up this iaterval between the pointed extremity of the enclosed 

 nucleus and the mouth of the crustaceous covering : there is no connexion whatever 

 between any part of this crustaceous coating and the enclosed seed, which lies quite free- 

 within it, and fills up its cavity. The raphe, consisting of a number of spiral vessels 

 enclosed in a delicate tube, is fii'st seen to issue from the umbilical cord ; it then finds its 

 way through one of the basal amucular lobes of the endoderm, in which a channel is seen 

 for its passage, after which it enters into the clear space between this crustaceous aril 

 and the integuments of the contained seed, and under the form of a perfectly free delicate 

 white thi'cad, it runs all round the margin of the seed, forming a complete circle, until it 

 again reaches the space within the mouth of the hilum, and when in the midst of the 

 deposition of tissue before mentioned, it changes its course suddenly inwards, and termi- 

 nates in the conical neck of the integument of the seed, by which the latter becomes thus 

 suspended : this conical neck is of a dark brown coloiu-, and is evidently the true chalaza 

 of the integument. The covering of the enclosed seed is thin and membranaceous, gene- 

 rally of a greenish hue, is quite smooth and evidently composed of two, if not of three pelli- 

 cular membranes, agglutinated into one thin integument. I have sometimes found this 

 structure more clearly demonstrated where the nucleus has become withered fr'om its 

 full dimensions ; it then appears as a large, perfectly transparent cyst, enclosing the 

 diminished embryo, and by transmitted light displays the deeper colouring of the chalaza 

 upon the inner membrane, which appears surrounded by another j^eUicle more trans- 

 parent at this point : the presence of the spiral vessels in the suspending thread, up to the 

 apex of the conical chalaza, is here perfectly distinct. At the other end of the integu- 

 mental covering of the seed, the one contrary to that of its suspension, is seen another 

 larger dark yellow areole, over the cotyledonary extremity of the embryo, and therefore 



