FLORIN: SYSTEMATICS OF THE GYMNOSPERMS 331 



out branching, or it may produce simple or ramified branches. The simul- 

 taneous progression of the arrest of the apical growth of the phyllopodium in 

 large-leaved vascular cryptogams and gymnosperms, and of the tendency of 

 the pinnae to develop in a basipetal succession, pointed to these phenomena 

 being mutually connected. 



Thibout (1896) investigated the morphology and anatomy of the male or- 

 gans and distinguished two main types of organization of the microsporoi)hyll, 

 viz., the leaf like, hyposporangiate cycadean type and the stalklike acrosporan- 

 giate gnetalean type. Lotsy (1899) believed that the Gnetales (chlamydosperms) 

 are equivalent to all other gymnosperms, and to the angiosperms, and of entirely 

 independent origin. 



The debate on the morphology of the female reproductive shoots in coni- 

 fers, taxads, and Ginkgo continued. The leading investigator was now Eichler 

 (1881, 1882a, 1882b, in Engler and Prantl, 1889), who, changing his earlier 

 opinion, adopted Sachs' view of 1868. The cone scales of all conifers are noth- 

 ing but open carpellary leaves, and the ovuliferous scales, where present, ventral 

 excrescences (ligulae, placentae) on these. Delpino (1889) and Penzig (1894) 

 rejected Eichler's interpretation, and instead thought that the ovuliferous scale 

 had arisen by the fusion of two lateral lobes of the bract. At first Celakovsky 

 (1882a, 1882b), conceded that the ligule of Araucaria might be regarded 

 as an excrescence on a carpel, but in 1884 he recanted this opinion and inter- 

 preted the Auraucaria cone like those of the Pinaceae. In view of the increas- 

 ing fusion of the bract to the ovuliferous scale, which is composed of carpels, he 

 assumed that the Pinaceae, Taxodiaceae, Cupressaceae, and Araucariaceae con- 

 stituted a phylogenetic series. In the taxads the ovule was displaced from the 

 axil to the apex of the uppermost leaf on the fertile short shoot. In 1890 (1898, 

 1900) Celakovsky stressed that ontogeny and teratological cases had undoubt- 

 edly proved the ovuliferous scale of the Pinaceae to be a short shoot. In the 

 main, it is reduced to two fertile, collaterally fused uniovulate carpels turning 

 their ventral sides towards the bract, and a sterile leaf, usually aborted, but in 

 the pine united with the carpels to form part of the ovuliferous scale. The female 

 conifer cones were also anatomically re-examined, particularly by Radais (1894) 

 and Worsdell (1899, 1900b). The latter finally (1900a) published a historical 

 study showing that the nature of the female reproductive parts of the conifers 

 and taxads remained the same unsolved problem as it was at the very begin- 

 ning of the nineteenth century. The female reproductive complex of Ginkgo and 

 Gnetum was also disputed. (Celakovsky I.e., Lotsy 1899). The old question of 

 the nature of the ovule and its integument is intimately connected with these 

 problems. 



Paleobotany made considerable progress in the period under review (Scott, 

 1900). The existence of a paleozoic group of plants, apparently combining char- 

 acters of ferns and cycads, had been recognized for some time. Grand' Eury 

 (1877) and Renault (1883) established the close similarity between the petioles 

 of the large fernlike fronds of AletJiopteris and Neuropteris preserved as im- 

 pressions and the detached petioles know^i structurally by the name of Myeloxy- 

 lon. Schenk (1889) and Weber and Sterzel (1896) proved that the Myeloxylon 

 type of petiole had been borne on MeduUosa stems. The foliage of medullosean 

 stems was therefore— at least partly— of the AletJiopteris and Neuropteris types. 



