174 

time the encircling ligneous zone of radiating vessels becomes yet 
more developed, both in the number of its vessels and in the 
diameter of the cylinder relatively to that of the entire stem. As 
these changes are produced, the medullary rays separating the 
lamince of the woody wedges become more definite, some of 
them assuming a more composite structure, and the entire 
organisation gradually assuming a more exogenous type, At 
the same time the cortical portions retain all the essential features 
of the Lepidodendroid plants. We are thus brought, by the 
evidence of internal organisation, to the conclusion that the 
plants which Brongniart has divided into two distinct groups, 
one ef which he has placed amongst the vascular Cryptogams, 
and the other amongst the Gymnospermous Exogens, constitute 
one great natural family. 
Stigmaria is shown to haye been much misunderstood, so far 
as the details of its structure are concemed, especially of late 
years. Inhis memoir of Sigid/aria elegans, published in 1839, 
M. Brongniart gave a description of it, which, though limited to 
a small portion of its structure, was, as far as it went, a remark- 
ably correct one. The plant, now well known to be a root of 
Sigdlaria, possessed a cellular pith without any trace of a distinct 
outer zone of medullary vessels, such as is universal amongst the 
Lepidodendra. The pith is immediately surrounded by a thick 
and well-developed ligneous cylinder, which contains two distinct 
sets of primary and secondary medullary rays. The primary ones 
are of large size, and are arranged in regular quincuncial order. 
They are composed of thick masses of mural cellular tissue. A 
tangential section of each ray exhibits a lenticular outline, the 
long axis of which corresponds with that of the stem. These 
rays pass directly outwards from pith to bark, and separate the 
larger woody wedges which constitute so distinct a feature in all 
transverse sections of this zone, and each of which consists of ag- 
gregated laminze of barred vessels, disposed in very regular radiating 
series. Thesmaller rays consist of vertical piles of cells, arranged in 
single rows, and often consisting of but one, two, orthree cellsineach 
vertical series. These latter are very numerous and intervening 
betweenall the numerous radiating Jaminze of vessels that constitute 
thelarger wedges of woody tissue. The vessels going to the rootlets 
are not given off from the pith, as Gceppert supposed, but from 
the sides of the woody wedges bounding the wfer part of the 
several large lenticular medullary rays ; those of the Zower por- 
tion of the ray takingno part in the constitution of the vascular 
bundles. The vessels of the region in question descend vertically 
and parallel to each other until they come in contact with the 
medullary ray, when they are suddenly deflected, in large num- 
bers, in an outward direction, and nearly at right angles to their 
previous course, to reach the rootlets. But only a small number 
reach their destination, the great majority of the deflected vessels 
terminating in the woody zone. A yery thick bark surrounds the 
woody zone. Immediately in contact with the latter it consists 
of a thin layer of delicate vertically elongated cellular tissue, in 
which the mural tissues of the outer extremities of the medullary 
rays become merged. Externally to this structure is a thick 
parenchyma, which quickly assumes a more or less prosenchy- 
matous form, and becomes arranged in thin radiating lamine, as 
it extends outwards, The epidermal layer consists of cellular 
parenchyma with vertically elongated cells at its inner surface, 
which feebly represents the bast-layer of the other forms of Lepi- 
dodendroid plants. The rootlets consist of an outer layer of 
parenchyma, derived from the epidermal parenchyma. Within 
this is a cylindrical space, the tissue of which has always disap- 
peared. Inthe centre is a bundle of vessels surrounded by a 
cylinder of very delicate cellular tissue, prolonged either 
from one of the medullary rays, or from the delicate innermost 
layer of the bark, because it always accompanies the vessels in 
their progress outwards through the middle and outer barks. 
The facts of which the preceding is a summary lead to the 
conclusion that all the forms of plants described are but modifi- 
cations of the Lepidodendroid type. The leaf-scars of the 
specimens so common in the coal-shales, represent tangential 
sections of the petioles of leaves when such sections are made 
close to the epidermal layer. The thin film of coal of which 
these leaf-scars consist, in specimens found both in sandstone and 
in shale, does not represent the entire bark as generally thought, 
and as is implied in the term “‘decorticated,” usually applied to 
them, but is derived from the epidermal layer. In such speci- 
mens, all the more central axial structures, viz., the medulla, the 
wood, and the thick layer of true bark, have disappeared through 
decay, having been either destroyed, or in some instances detached 
and floated out ; the bast-layer of the epiderm has arrested the 
NATURE 

| Fune 29, 1871 

destruction of the entire cylinder, and formed the mould into 
which inorganic materials have been introduced. On the other 
hand, the woody cylinder is the part most frequently preserved 
in Stigmaria; doubtless because, being subterranean, it was 
protected against the atmospheric action which destroyed so much 
of the stem. 
It is evident that all these Lepidodendroid and Sigillarian plants 
must be included in one common family, and that the separation 
of the latter from the former as a group of Gymnosperms, and as 
suggested by M. Brongniart, must be abandoned. The remark- 
able development of exogenous woody structures in most mem- 
bers of the entire family indicates the necessity of ceasing to 
apply either to them, or to their living representatives, the term 
Acrogenous. Hence the author proposes a division of the 
vascular Cryptogams into an Exogenous group, containing Zyco- 
podiacee, Eguisetacee, and the fossil Ca/amitacee, and an Endo- 
genous group containing the Ferns; the former uniting the 
Cryptogams with the Exogens through the Cycadee and other 
Gymnosperms, and the latter linking them with the Endogens 
through the Palmacee. 
“«Contributions to the History of the Opium Alkaloids. 
Part II. On the Action of Hydrobromic Acid on Codeia and 
its derivatives.” By C. R. A. Wright, D.Sc. It has 
been shown in Part I. of this research* that the action of 
hydrobromic acid on codeia gives rise, without evolution of 
methyl bromide, first to bromocodide, and secondly to two 
other new bases termed respectively deoxycodeia and bromote- 
tracodeia, the latter of which, under the influence of hydro- 
chloric acid, exchanges bromine for chlorine, yielding a corre- 
sponding chlorinated base, chlorotetracodeia; when, however, 
the action of hydrobromic acid is prolonged, methyl bromide is 
evolved in some little quantity. By digesting codeia with three 
or four times its weight of 48 per cent acid for five or six hours 
in the water-bath, vapours were evolved which, condensed by 
the application of a freezing-mixture to a colourless mobile 
liquid, the borling-point of which was found to be 10°°5 to 11°°5, 
and the vapour of which burnt with a yellow-edged flame, ex- 
ploded violently with oxygen, forming carbonic and hydro- 
bromic acids. It becomes, therefore, of interest to examine in 
detail the action of hydrobromic acid on each of the three bodies 
produced from codeia under its influence. 
“ On the Physiological Action of the foregoing Codeia deriva- 
tives.” By Michael Foster, M.D. The hydrochlorate of 
chlorotetracodeia and the hydrobromate of bromotetramorphia, 
in doses of a decigramme by subcutaneous injection or 
by the mouth, produced in adult cats in a very few 
minutes a condition of great excitement, almost amounting to 
delirium, accompanied by a copious flow of saliva and great 
dilatation of the pupils. Nicturation and de‘zecation occurred in 
some instances, and vomiling was observed on two occasions 
with the morphia-salt, but was very slight. The excitement was 
very peculiar, being apparently due partly to increased sensitive- 
ness to noises, and partly to an impulse to rush about. 
The same doses of the morphia-salt given to a young kitten 
produced the same flow of saliva, dilatation of pupils, and 
excitement (without vomiting); but the stage of excitement, 
which in adult cats passed gradually off in a few hours, was 
followed by a condition marked by a want of co-ordination of 
muscular movements, and presenting the most grotesque re- 
semblance to certain stages of alcoholic intoxication. This 
stage was followed in turn by sleepiness and stupor, in 
which the kitten was left at night ; in the morning it was found 
dead, 
Two observations have shown that these salts paralyse (in dogs 
and cats) the inhibitory fibres of the pneumogastric ; they also 
seem to Jower the internal tension, but want of material has 
prevented me from ascertaining how this is brought about. 
On rabbits neither salt, even in doses of a decigramme, seems 
to have any effect, except perhaps a slight excitement. There 
is no dilatation of the pupils, no flow of saliva, and, if one 
observation can be trusted, no paralysis of the inhibitory fibres 
of the pneumogastric. 
No marked difference was observable between the two salts, 
except that the morphia salts seemed rather more potent than 
the corresponding codeia bodies. 
The salts of deoxycodeia and deoxymorphia given by mouth or 
by subcutaneous injection in doses of a decigramme, produced in 
adult cats, almost immediately after exhibition, a series of con- 
* Proc. Roy. Soc. vol, xix. p. 372 
