THE SEQUENCE OF ANTICLINES AND PERICLINES VARIES. 



443 



Fig. 27S.— .-? a very young, B an older embryo of Orobanche (after Koch). 



A B the resemblance to our scheme is again perceived at once, although the outlines 

 can hardly pass as ellipses. Besides, we have here the case that the organ which 

 we are considering as cut up into cells simultaneously with growth is provided on 

 the one side with a stalk. In such cases a hypophysis (Ji) regularly makes its 

 appearance at the boundary be- 

 tween stalk and head. Hanstein ^ B 

 formerly held this to be an organ 

 peculiar to the embryos of Pha- 

 nerogams : it is, however, nothing 

 further than the expression of the 

 general law of cell-division for the 

 case here given. 



In these figures we meet with 

 yet another fact of experience, in 

 that the sequence in time in the 

 origin of the anticline and peri- 

 cline walls, even in very similar 

 objects, is variable in a high 

 degree. Sometimes, as in Fig. 

 277 A, numerous anticlines are 



produced, the periclines (/> in E) only following subsequently ; or periclines arise 

 followed at once by the anticlines, as in Fig. 278 B, But even this in no way alters 

 the validity of the scheme described above, in the construction of which it is of course 

 immaterial whether the anticlines or the periclines are drawn first. 



As a rule, the external form of very young organs which still consist of 

 embryonic substance changes as 

 they gradually develope. Hence 

 the case occurs not rarely that 

 walls which have already been 

 produced undergo displacements 

 and curvatures during the alter- 

 ation in form of the entire struc- 

 ture, in such a manner that they 

 now become adapted to the new 

 form of the organ as if they had 

 only been produced after its at- 

 tainment. Since this case, hither- 

 to little noticed, is of peculiar im- 

 portance for the theory of growth, 

 because it throws new light on 

 the intercalations and movements fig. 279. 



taking place in the embryonic 



mass of tissue, I may here adduce an illustrative scheme and an example. In Fig. 

 279 to the left is represented a filamentous structure, which is divided by several 

 transverse walls TT and by one series of longitudinal walls. The figure on the right 

 shows us the same structure after the filament has become transformed into a stalked 



