5o6 



NATURE 



[Sept. 20, 1883 



The flattened specimen ran obliquely along the roof, each of its 

 two extremities passing out of sight, burying themselves in the 

 opposite sides of the mine. Yet the portion which we measured 

 was 30 feet long, its diameter being 6 inches at one end, and 

 4I inches at the other. The mean length of its internodes at its 

 broader end was 3 inches, and at its narrower one it inches 

 What the real thickness of this specimen was when all its tissues 

 were present we have no means of judging, but the true 

 diameter of the cylinder represented by the fossil when un- 

 compressed has been only 4 inches at one end of the 30 feet, 

 and 2i inches at the other. Whatever its entire diameter when 

 living, the vascular cylinder of this stem must have been at once 

 tall and slender, and consequently must have required some 

 " Appareil de soutien," such as its exogenous vascular zone did 

 not supply. This was provided in a very early stage of growth 

 by the introduction of a second cambium-layer into the lark; 

 which, though reminding us of the cork-cambium in ordinary 

 exogenous stems, produced not cork but prosenchymatous cells. 1 

 In its youngest state the bark of the Catamites was a very loose 

 cellular parenchyma, but in the older stems much of this paren- 

 chyma became inclosed in the prosenchymatous tissue referred 

 to, and which appears to have constituted the greater portion of 

 the matured bark. The sustaining skeleton of the plant, there- 

 fore, was a hollow cylinder developed cenlrifugally on the inner 

 side of an inclosing cambium-zone. That this cambium-zone 

 must have had some protective periderm external to it is 

 obvious ; but I have not yet discovered what it was like. We 

 shall find a similar cortical provision for supporting lofty crypto- 

 gamous stems in the Lepidodendra and Sigillarim. 



The Carboniferous rocks have furnished a large number of 

 plants having their foliage arranged in verticils, and which have 

 had a variety of generic names assigned to them ; such are 

 Asterophyllitcs, Sphcnophyllum, Annularia, Bechera, Hippurites, 

 and Schizonenra. Of these genera, Sphcnophyllum is dis- 

 tinguished by the small number of its wedge-shaped leaves, and 

 the structure of its stems has been described by M. Renault. 

 Annularia is a peculiar form in which the leaves forming each 

 verticil, instead of being all planted at the same angle upon the 

 central stem, are flattened obliquely nearly in the plane of the 

 stem itself. Asterophyllitcs differs from Sphcnophyllum, chiefly 

 in the larger number and in the linear form of its leaves. Some 

 stems of this type have virtually the same structure'- as those of 

 Splienophyllum, a structure which differs widely from that of the 

 Calamites, and of which, consequently, these plants cannot 

 constitute the leaf-hearing branches. But there is little doubt 

 that true Calamitean branches have been included in the genus 

 Asterophyllitcs ; I have specimens, for which I am indebted to 

 Dr. Dawson, which I should unhesitatingly have designated 

 Asterophyllitcs but for my friend's positive statement that he 

 detached them from stems of a Calamite. Of the internal 

 organisation of the stems of the other genera named we know 

 nothing. 



It is a remarkable fact that, notwithstanding the number of 

 young Calamitean shoots that we have obtained from Oldham 

 and Halifax in which the structure is preserved, we have not 

 met with one with the leaves attached. This is apparently due 

 to the fact that most of the specimens are decorticated ones. 

 We have a sufficient number of corticated specimens to sin™ us 

 what the bark was, but such specimens are not common. They 

 clearly prove, however, that their bark had a smooth, and not a 

 furrowed, external surface. 



There yet remains for consideration the numerous reproductive 

 strobili, generally regarded as belonging to plants of this class, 

 Equisetiinv. We find some of these strobili associated with 

 stems and foliage of known types, as in Spheuophyllum, 3 but we 

 know nothing of the internal organisation of these Sphenophyl- 

 loid strobili. We have strobili connected with stems and foliage 

 of Annularia, 4 but we are equally ignorant of the organisation 

 of these ; so far as that organisation can be ascertained from 

 Sterzel's specimen, it seems to have alternating sterile and fertile 

 bracts with the sporangia of the latter arranged in fours, as in 

 Calamostaehys. b On the other hand, we are now very familiar 

 with the structure of the Calamostachys Binneana, the prevalent 

 strobilus in the calcareous nodules found in the lower coal- 



* " Memoir" ix. PI. xx. Figs. 14, 15, 18, 19, and 20. 



- " Memoir," Part v. Plates i. — v., and Part ix. PI. xxi. Fig. 32. 



3 Lesquereux, " Coal Flora of Pennsylvania," PI. ii. Fig. 687. 



4 " Ueber die Fruchtahren von Annularia Sphenophylloides." Von 

 T. Sterzel, "Zeitschr. d. Deutschen Geolog. Gesellschaft," Jahrg. 1882. 



5 M. Renault has described a strobilus under the name of Anuulalia 

 longifolia. but which appears to me very distinct from that genus. 



measures of Lancashire and Yorkshire. It has evidently been a 

 sessile spike, the axial structures of which were trimerous 1 

 (rarely tetramerous), having a cellular medulla in its centre. 

 Its appendages were exact multiples of those numbers. Of the 

 plant to which it belonged, we know nothing. On the other 

 hand, we have examples, supposed to be of the same genus, as 

 C. paniculata," and C. polystachya, 3 united to stems with 

 Asterophyllitean leaves, but whether or not these fruits have the 

 organisation of C. Binneana, we are unable to say. 



We are also acquainted with the structure of the two fruits 

 belonging to the genera Bruckniannia 4 and Volkmannia.'' This 

 latter term has long been very vaguely applied. 



There still remain the genera Stachannularia, Pahcostachya, 

 Macrostachya, Cingularia, Ifut/onia, and Calamitina, all of 

 which have the phyllomes of their strobili, fertile and sterile, 

 arranged in verticils, and some of them display Asterophyllitean 

 foliage. But these plants are only known from structureless im- 

 pressions. That all these curious spore-bearing organisms have 

 close affinities with the large group of the bquisetums cannot 

 be regarded as certain, but several of them undoubtedly have 

 peculiarities of structure suggestive of relations with the 

 Calamites. This is especially observable in the longitudinal 

 canals found in the central axis of each type, apparently identical 

 w ith what I have designated the internodal canals of the 

 Calamites." The position and structure of their vascular 

 bundles suggest the same relationship, whilst in many the posi- 

 tion of the sporangia and sporangicphores is eminently Equiseti- 

 form. Renault's Bruckniannia Grand-Euryi, and B. Decaisnei, 

 and a strobilus which I described in 1S70," exhibit these Cala- 

 mitean affinities very distinctly. 



One strobilus which I described in 1880 8 must not be over- 

 looked. As is well known, all the living forms of Equisetaceous 

 plants are isosporous. We only discover heterosporous vascular 

 cryptogams amongst the Lycopodiacea, and the Rhizocarpcc. My 

 strobilus is identical in every detailed feature of its organisation 

 w ith the common Calamostachys Binneana, excepting that it is 

 heterosporous, having microspores in its upper and macrospores 

 in its lower part ; a state of things suggestive of some link 

 between the Equiselina and the heterosporous Lycopodia, 



Lycopodiacea. — This branch of my subject suggests memories 

 of a long conflict which, though it is virtually over, still leaves, 

 here and there, the ground-swell of a stormy past. At the 

 meeting of the British Association at Liverpool in 1870, I first 

 announced that a thick, secondary, exogenous growth of vascular 

 tissue existed in the steins of many Carboniferous cryptogamic 

 plants, especially in the Calamitean and Lepidodendroid forms. 

 But, at that time, the ideas of M. Brongniart were so entirely 

 in the ascendant, that my notions were rejected by every botanist 

 present. Though the illustrious French palaeontologist knew 

 that such growths existed in Sigillo.ru? and in what he designated 

 Calamodendra, he concluded that, de facto, such plants could 

 not be Cryptogams. Time, however, works wonders. Evidence 

 has gradually accumulated proving that — with the conspicuous 

 exception of the ferns — nearly every Carboniferous Cryptogam 

 was capable of developing such zones of secondary growth. 

 The exceptional position of the ferns still appears to be as true 

 as it was when I first proclaimed their exceptional character at 

 Liverpool. At that time I was under the impression that the 

 secondary wood was only developed in such plants as attained 

 (o arboreal dimensions, but I soon afterwards discovered that it 

 occurred equally in many small plants like Sphcnophyllum, 

 Asterophyllitcs and other diminutive types. 



After thirteen years of persevering demonstration, these views, 

 at first so strongly opposed, have found almost universal ac- 

 ceptance. Nevertheless, there still remain some few who believe 

 them to be erroneous ones. In the later stages of this discussion 

 the botanical relations subsisting between Lepidodendron, Sigit- 

 laria, and Stigmaria have been the chief themes of debate. In 

 this country we regard the conclusion that Stigmaria is not only 

 a root, but the root alike of Lepidodendron and Sigillatia, as 

 settled beyond all dis| ute. Nevertheless M. Renault and M. 

 Giand-Eury believe that it is frequently a leaf-bearing rhizome, 



1 It is an interesting fact that transverse sections of the young strobili of 

 Lycpftcdium Al/ittnm exhibit a similar trimerous arrangement, though 

 differing widely in the positions of itsspcrangia. 



Weiss, " Al>handlungenzurGeologischen Specialkarte von Preuszen und 

 Thfirinaischen Staaten," Taf. xiii. Fig. 1. 3 Idem. Taf. xvi. Figs. 1, 2. 



4 Renault. " Annales de Sciences naturelles," Bot, Tome iii. PI. iii. 



5 Idem. PI. ii. 



6 " Memoir " i. PI. xxiv. Fig. 14*-, and PI. xxvi. Fig. 24 e. 



7 " Memoirs of the Literary and Philosophical Society of Manchester," 

 3rd series, vol. iv. p. 248. 8 "Memoir" xi. PI. liv. Figs. 23, 24. 



