ANTICLINES AND PERICLINES IN SOLID STRUCTURES. 447 



of the form of a watch-glass, or, since according to our construction the anti- 

 clines A are hyperbolas, each of the walls A would represent a hyperbolic surface 

 in the body of the embryo, and in like manner the periclines F and p would 

 represent portions of ellipsoidal surfaces. The further growth and formation of 

 organs in this embryo then proceeds by means of the cells 3, sf, and w, which 

 arise in the octants. In the two lower octants to the left, two cells (as s/) are 

 formed: these are the so-called apical cells, of which, however, only one is con- 

 cerned with the further growth, and constitutes the apex of the stem of the young 

 Fern. This apical cell of the stem has the form of a tetrahedron (cp. Fig. 269, 

 above) in which, as growth proceeds, new division-walls continually appear parallel 

 to the anticlines. The same happens also in the apical cell of the first root w, 

 where, however, in addition to the anticlinal segmentations parallel with A and a, 

 pericline-walls p are also cut off for the formation of the root-cap. In accordance 

 with the origin there are properly also two such root-rudiments present in the octants 

 situated to the right above, but the actual formation of a root takes place in one of 

 them only. The apical cell 5 becomes united with the corresponding one of the 

 octant lying next it for the formation of the first leaf of the embryo Fern. 



We here become acquainted with a new relation between cell- division and 

 growth. From what has been said it may be observed that certain cells, previously 

 determined by the general law of growth in the embryo, make themselves evident as 

 the points of origin of the new organs of the stem [sf), of the root {tv), and of the 

 first leaf {ö) ; and with respect to the apical cells si and w which, as stated, possess 

 the form of a tetrahedron, the important fact may here be brought forward that the 

 production of these apical cells is a necessary consequence of the law of cell-division 

 prevailing in the embryo. This observation is of importance, because, until the 

 appearance of my investigation on the arrangement of cells, the causal relation was 

 believed to be an entirely different one. Indeed, people went so far as to regard the 

 fertilised oosphere itself as the first apical cell of the stem ; just as, in general, an 

 entirely unwarranted importance had been attributed up to that time to the apical 

 cells which are found in the growing-points of many Cryptogams. This will become 

 clearer in the sequel. 



The subject of the relation between growth and cell-division in the growing- 

 points of shoots and roots is more difficult than in the cases considered hitherto ; but 

 even here I have succeeded in making the facts clear on the principles laid down at the 

 commencement of this lecture, after hundreds of careful investigations on the cellular 

 network of the growing-point had provided material, welcome and valuable, it is true, 

 but by no means intelligible. Just as do the organs hitherto considered, which 

 consist entirely of embryonic substance, so also do the growing-points of roots 

 and shoots show characteristic cell-wall networks or cell-arrangements on properly 

 directed longitudinal and transverse sections, and these everywhere, even in the most 

 different species of plants, agree with the type. This depends essentially upon the 

 fact that the embryonic substance of the growing-points, as it increases in volume on 

 all sides, becomes divided up into compartments, or chambers, by cell-walls which 

 cut one another at right angles. The longitudinal section of a growing-point always 

 shows a system of periclines, cut by anticlines which in their turn constitute 

 the orthogonal trajectories of the former. If we arc here concerned with growing- 



