MORPHOLOGY OF THE OVULE 157 



so-called seed scales, which bear the ovules or megaspor- 

 angia. These seed scales arise in the axils of the bract 

 scales and, since we are unacquainted with any case of a 

 ' folium in axilla folii/ we must conclude that the ' seed 

 scale ' is a modified axillary organ, and hence that the 

 cone of Abies is an inflorescence." Lotsy supports his 

 views with anatomical evidence, but the matter is of too 

 controversial a nature to discuss in a course of lectures 

 like the present. 



Under the influence of the views on metamorphosis 

 held by botanists about 1860, the stamen was regarded 

 as a leaf whose half-blades had become transformed into 

 pollen-sacs, but the recognition of the pollen grain as a 

 microspore gradually led botanists to regard the pollen- 

 sac as a microsporangium, a view emphasised by Goebel 

 in 1881 after its anatomy and development had been 

 worked out by Warming in 1873. 



The ovule gave far more trouble. According to 

 Schleiden and Braun it was a bud arising from a axial 

 placenta, and consequently the integuments represented 

 fused leaves. In his textbook Sachs gives different 

 morphological significations to the ovule according to 

 its mode of origin and position. A terminal ovule is of 

 an axial nature, a lateral ovule is a modified leaf, a 

 marginal one is a branch of a leaf, while a superficial one 

 is to be included " in the category of such foliar out- 

 growths as we have already found to occur in the form 

 of sporangia among the Lycopodinae. The ovules of 

 Orchideae must, however, be included under the category 

 of trichomes, in as much as they owe their origin to simple 

 superficial cells of the parietal placentae." By 1881, 

 however, the general opinion was that the ovule was a 

 megasporangium and that the embryo-sac was a spore 

 mother cell, which became a megaspore with or without 

 division, and hence that the cellular tissue ultimately 

 formed in it corresponded to a female gametophyte. 

 This view was put forward by Strasburger, who also held 



