134 



PRINCIPLES OF PLANT-TERATOLOGY. 



axillary shoots in Angiosperms, it is highly probable 

 that the subaxillary, petiolar position in Cycads repre- 

 sents the condition from which the truly axillary 

 position in Angiosperms has been derived. Dr. Stopes' 

 observation strongly supports Celakovsky's view of the 

 matter. 



Adventitious shoots occur, often as quite normal 

 features, on the upper surface of the blades and petioles 

 of many ferns, such as Asplenium bulbiferum and other 

 species, Aspidium Filix-Mas, Athyrium Filix-foemino, 

 Pteris aquilina, Gymnogramme chrysophyllum, and 

 Poly podium proliferum. They occur normally on the 

 lower surface in Gystopteris bulbifera. 



The phenomenon may be correlated with the damp 

 habitat of most ferns In some cases, however, as in 

 those of Pteris quadriaurita and Aspidium aristatum, 

 they arise under the influence of the Fungi Taphrina 

 Laurencia and T. Cornu-cevvi respectively. 



According to Goebel, the fern Adiantum Fdgwovtliii 

 produces adventitious shoots at the actual apex of the 

 leaf whose apical cell divides into two, and from one 

 of the two daughter-cells the adventitious shoot is 

 developed ; this, therefore, is exactly comparable to 

 what occurs in the roots of the ferns Diplazium and 

 Platycerium. 



Kupper found that in species of Adiantum and in 

 Asplenium prolongatum the apical cell of the adven- 

 titious bud proceeds directly from that of the leaf. In 

 the former genus the first three leaves of each bud arise 

 from the thickened tip of the leaf quite away from the 

 new vegetative apex ; in the Asplenium this is the case 

 only with the first leaf. The first roots arise endo- 

 genously on the convex side of the apex of the 

 mother-leaf ; the later ones on the axis of the bud. 

 In Aneimia rotundifolia the leaf -rudiments may arise 

 before the shoot-apex is present ; and he found that 

 the first leaves (as many as six) arise quite indepen- 

 dently of the shoot-apex, although normally orientated 

 thereto, and in perfectly regular arrangement. This, 



