70 MORPHOLOGY OF SPERMATOPIIYTES 



other cones he found the two parts of the ovuliferous scale in 

 all stages of coalescence. All of his material confirmed Braun's 

 view that the ovuliferous scale is made up of the first two leaves 

 of an axillary shoot, which stand transversely, and are connate 

 by their axial edges. It may be of interest to note in this con- 

 nection that such a view would refer the megasporangia to the 

 niorpholpgically under surface of the leaf, and in so doing would 

 make them conform with the microsporangia in this respect. 



In the same year (1876) Engelmann, 19 in reviewing Sten- 

 zel's paper, reported similar monstrosities in cones of Picea 

 Engelmanni and Tsuga Canadensis. 



In 1879 Celakovsky 23 > 25 > 29 > 35 began publishing upon the 

 subject, and has constructed a theory which seems to unify more 

 nearly than any other the puzzling diversities of structure. In 

 the first place, he regards the ovuliferous scale as the repre- 

 sentative of an axillary shoot, confirming in general Braun's 

 view. He states that in this case " Nature takes a short cut," 

 the ovuliferous scale being formed directly, rather than an axis 

 with two distinct lateral leaves. Moreover, he sees in the ovu- 

 liferous scale, which has assumed a permanently vegetative char- 

 acter, the modified and blended outer integuments of the two 

 ovules. Therefore, there is present no true carpel in Conifers, 

 this structure being reduced, so to speak, to a single ovule. The 

 microsporophyll corresponds to the bract of the megasporangiate 

 cone, which subtends the axis which bears the hypothetical 

 megasporophyll (represented only by the ovule), the latter 

 being on a shoot of higher order. As a consequence, the axillary 

 ovuliferous structure corresponds to the axillary spur shoot of 

 Ginkgo and the main axis of Cycads. In applying this doc- 

 trine of an outer integument in all Conifers, Celakovsky reaches 

 the following conclusions: In the Taxaceae, certainly the older 

 of the tw r o great groups of Conifers, the two normal integu- 

 ments are evident, being distinct in Taxus, Dacrydium, and 

 Microcachrys (the outer being the " aril "), and represented by 

 the fleshy and bony layers of the seed in Cephalotaxus and 

 Podocarpus, as in Cycads and Ginkgo. In Araucarieae, Abie- 

 teae, and Cupresseae, the outer integument is the ovuliferous 

 scale (or half of it), being developed after the sporangium and 

 showing the inverted orientation, facts true of all outer integu- 

 ments. In this outer integument he sees the ligule of Isoetes 



