Oct. 22, 1885] 
NATURE 
395, 
The important influence of cuticular wax and epidermal 
hairs upon transpiration is also discussed. 
In Section IV. the mechanical system is considered. 
With much of the subject-matter of this section we have 
been acquainted since the appearance of Schwendener’s 
classic ‘‘Das mechanische Princip ;” but it is of interest 
to note that in the fungi, e.g. Usnea barbata, evidence 
exists of a mechanical tissue which in the higher plants 
takes the form of sclerenchyma, collenchyma, and bast. 
The absorptive system includes roots, rhizoids, and like 
structures ; attention being also drawn to the absorptive 
tissue of the scutellum. This organ in Ariza niznor is 
peculiar on account of the pronounced development of 
the absorptive cells, and their striking resemblance to root 
hairs. 
Section VII. deals with the assimilative system, and 
oneis much struck by the marked manner in which the 
whole structure of the leaf illustrates the principles of 
which Dr. Haberlandt is the exponent. The pallisade 
layers are naturally regarded as being the chief seat of 
assimilative activity, and it is pointed out that the cells 
below these layers, which are of the nature of spongy 
parenchyma, and contain comparatively few chlorophyll 
grains, are distinguished by the remarkable manner in 
which they abut on to the pallisade cells. Their special 
function appears to be to conduct or absorb the products 
of assimilation, and to be the means of conveying them 
to other parts of the plant. They are in consequence 
designated as receptive or conducting cells (Aufnahme 
oder Sammelzellen). The infoldings which occur in 
numerous pallisade cells and are so well developed in the 
leaf of the various species of Pinus, have for their object 
the increasing of surface-area, and consequently also the 
number of chlorophyll grains in the cell. 
Some space is devoted to the consideration of the con- 
ducting system, which includes the parenchyma of the 
cortex. and pith, the medullary ray parenchyma, &c., the 
vascular bundles and laticiferous tissue. 
Dealing with the vascular bundles from the point of 
view of physiological anatomy, a special terminology has 
been adopted. The whole bundle is known as the 
Mestom, the xylem as the Hadrom, and the phloem as the 
Leptom. The idea of Mestom includes purely vascular 
tissue, and excludes the mechanical sclerenchymatous 
and fibrous tissue (stereom), consisting usually of 
prosenchymatous cells (steréides), such as occur ac- 
companying the bundles of most monocotyledons. Dr. 
Haberlandt’s experiments demonstrate that in the moss 
stem the central strand of tissue is to be regarded as 
consisting of rudimentary hadrom, having for its function 
the conduction of water. To the layer surrounding the 
vascular bundle in roots, &c. (endodermis of De Bary) is 
applied the term “protective sheath,” or “ protective 
layer,” on account of its function with relation to the 
bundle. 
For a more complete understanding of the nature of 
laticiferous tissue we are again indebted to Dr. Haber- 
landt, whose observations upon this point appear to be 
of extreme importance. These observations demon- 
strate that in many of the thick-leaved Euphorbias, those 
portions of the laticiferous cells which enter the leaf 
become repeatedly branched in the leaf-tissue, and in 
such a manner that the extremities or blind ends of these 
branches abut directly on to the pallisade parenchyma 
cells, and are thus brought into the closest possible relation 
with the seat of greatest assimilative activity. The 
natural inference as to the function of laticiferous tissue 
has consequently everything to be said in its favour. 
In Section IX. the intercellular space system is dealt 
with, and the various forms of stomata and their me- 
chanism described. Much importance must necessarily 
be attached to this system when one bears in mind the 
relation of transpiration and gaseous diffusion to plant- 
life. The remaining sections are devoted to the secretory 
and excretory organs, and to the phenomena attending 
the normal and abnormal mode of increase in thickness 
of the stem and root. 
The few remarks that have already been made are 
sufficient to show that the book contains numerous points 
of much interest. It is, moreover, carefully written, and 
furnished with a copious bibliography. 
We cannot conclude this review without pointing out 
as Dr. Haberlandt has so fitly done, the importance of 
recognising that in every system there is not only the 
chief, but also the subsidiary, function, and that in con- 
sidering any one of them which is especially significant, 
the less pronounced but still existing functions must be 
kept in mind. By such means alone will the true 
advance of physiological anatomy be maintained. 
W. G. 
WILLIAM HEDLEY 
William Hedley, the Inventor of Railway Locomotion 
on the Present Principle. By M. Archer. Third 
Edition. (London: Crosby Lockwood and Co., 
1885.) 
N this little book the author endeavours to place on 
record more exact facts with regard to the invention 
of the locomotive, and to give prominence to the name of 
the man who first made the locomotive a practical and 
financial success. 
Richard Trevithick is perhaps the only man, before 
Hedley’s time, who narrowly missed the fame now 
accredited to Stephenson and Hedley. In 1808 Trevi- 
thick constructed a circular railway in a field, now 
forming the southern half of Euston Square. On this 
railway he placed a locomotive of his own construction, 
having flanged wheels, a tubular boiler, and a vertical 
cylinder, driving by means of a cross head the hinder pair 
of wheels. This engine was attached to a coach, and the 
few people who would venture in it were taken round the 
railway at so much per head. After running for a few 
weeks, a rail broke, causing the engine to leave the 
rails, and turn over on its side. At this time Trevithick 
had expended all his means, and was compelled to give 
up his endeavours to convince the public of the many 
advantages to be obtained from the use of the locomotive ; 
had he been backed up by influential men, no doubt he 
would now be known to fame as its inventor. 
Many men before Hedley’s time had tried their utmost 
to make a workable locomotive, such as would supersede 
horses on a colliery railway. Trevithick, Blenkinsop, 
and Chapman all exercised great ingenuity in their de- 
signs, but success was as far off as ever, owing to the 
general idea prevailing that some mechanical connection 
must exist between the engine and the railway, believing 
