446 



LECTURE XXVII. 



Our space being limited, however, it must be left to the reader to reflect upon the 

 matters in question. I will only refer to one particular case, since it is common every- 

 where. When an ellipsoidal, or spherical, or similar body becomes divided, walls 



regularly occur in three direc- 

 tions, cutting one another at right 

 angles, in such a manner that 

 the body is first cut by a wall into 

 two usually equal halves, each of 

 which is then bisected by a wall 

 standing at right angles to the 

 first wall, and then a wall at right 

 angles to the first and second 

 cuts the whole into eight octants. 

 In each of these, anticlinal and 

 periclinal cell- walls now appear, so 

 that transverse and longitudinal 

 sections give figures such as we 

 have already considered. Here, 

 as already said, it is of no mo- 

 ment whether we regard the capi- 

 tulum of a hair, an embryo, an 

 antheridium, or any other organ. 

 For example. Fig. 283 represents 

 a median longitudinal section (of 

 course very diagrammatic) of the 

 embryo of a Fern, produced from 

 the fertilised oosphere. The anticlines and periclines are at once recognised as we 

 constructed them in our scheme for an elliptical disc, particularly in the case of the 

 walls marked Aa and Pp. In order to obtain an idea of the true state of aff"airs in this 



case, however, we must suppose 

 A ^^-^ I ~~~~~-^^ the figure to have made a complete 



revolution round the long axis 

 of the ellipse and thus described 

 an ellipsoid in space. The draw- 

 ing then represents only a median 

 longitudinal section of this ellip- 

 soid, the entire cellular structure 

 of which would only be perceived 

 when also viewed from above, 

 from below, from behind, and 

 from before. It would then be 

 p,G. 283. found, moreover, that the whole 



ellipsoid is also completely di- 

 vided by a wall in the plane of the paper, and thus that not merely four 

 quadrants are present, as our figure shows, but eight octants. In each of these 

 octants, again, there has arisen in the first place an anticline, A^ approximately 



Fig. 282.— Transverse section of the wood of a 'iJ\w\e{Tilea platyphytlos). 

 St medullary rays; ap fissures produced by drying; zside of feeblest, a that 

 of strongest growth in thickness. 



