CERTAIN STEUCTUEES IN THE GENUS GNETUM. 315 



the base of the female flower of Gnetum Gnemon''*, afford some support to the view 

 that the primitive inflorescence from which the present complex spikes have arisen was 

 of the nature of an axis bearing a terminal ovule surrounded by a single ring of male 

 flowers * (or perhaps anthers). 



In the ovule with four integuments, referred to above (fig. 2), there is no trace of the 

 *'ring of complex groups of vascular strands " described by Miss Berridge for the normal 

 ovule with three envelopes, but the three lower of the envelopes possess an apparently 

 equivalent vascular supply. This might, perhaps, be regarded as indicating tliat this 

 reduced ring of vascular tissue is a vestige, not of a ring of male elements, as Miss Ber- 

 ridge suggests f, but of a missing fourth envelope. On the other hand, it will be seen 

 on reference to the figure that the second and third envelopes appear to arise from 

 a common base — indicating, perhaps, a doubling of the original middle integument. 

 This suggestion is of interest when compared with the accounts given of the development 

 of the incomplete female flowers. Lotsy % finds that a middle envelope is present in 

 a rudimentary condition in the younger stages, but later is unrecognizable. It therefore 

 seems probable that the middle envelope is less stable in character than either of the 

 other two ; that it is liable to be suppressed or duplicated according to circumstances. 

 It is at least improbable that the outermost envelope is supernumerary. Before it was 

 cut, the ovule enclosed in its envelopes had a perfectly normal appearance, and there 

 was nothing to suggest that its outer covering was in any way different from that of an 

 ordinary complete female flower, and as far as the outer envelope itself is concerned, 

 this resemblance is seen also in the sections. In any case, it is clear that in the present 



^ 



state of our knowledire some desrree of caution should be exercised in assigning any of 



O^ "— 3 



the three normal envelopes to a particular morphological category. 



The same ovule shows another feature of interest which appears not to have been 

 previously described. A tangential section (fig. 3) shows a bud arising between the 

 outer and the succeeding envelopes [b). As this is the only instance of the kind 

 observed, it is not certain that the bud stands opposite the median line of one of the 

 primaries from which the outer envelope is derived. Also its vascular supply cannot be 

 determined at this stage. It may, however, be presumed that it is truly axillary. 

 If so, the foliar character of this envelope is beyond doubt. If the view suggested 

 above, that the middle integument in this ovule is duplicated, is correct, and the outer- 

 most of the four envelopes is therefore homologous with the outermost of the three of 

 a normal flower, an interesting conclusion is suggested by the presence of this axillary 

 bud. For it shows that there exists a tendency to the development of axillary structures 

 by which the spike of Gnetum might arise by " proliferation " from a primitive 

 inflorescence (or flower) bearing a single terminal ovule. A similar origin for the male 

 spike of JFehoitschia has already been suggested by Wieland §. Also, if this is the true 

 outer envelope, the presence of a bud in its axil is in favour of the conclusion that 

 the origin of the flower-envelope of the Gnetales is to be sought, not in the sterilization 



* Pearson, 1912. t ^^^nis^, 1912. 



t Lotsy, 1S99. § ^VielaDd, 1908. 



