588 
In some experiments on Ricinus which I carried out in 1889, 
I found much the same sequence of events as Van Tieghem had 
described. The endosperm unquestionably became the seat of 
a renewed metabolism, in the course of which many interactions 
between the various reserve materials became noticeable. It 
was remarkable that the activity of this metabolism was much 
more pronounced when the embryo or parts of it were left in 
contact with the endosperms. 
An observation of a similar character has been made by 
Haberlandt and by Brown and Morris in the case of the seeds 
of grasses. The conversion of the reserve cellulose of barley 
grains has been shown by these observers to be the result 
of the action of an enzyme cyfase, which is secreted largely 
by the so-called aleurone layer, which is found surrounding the 
endosperm, immediately underneath the testa. 
Recently my own work has been bearing on this question, 
particularly as regards the behaviour of the seeds of Ricinus 
during germination. ‘The reserves of this seed are mainly com- 
posed of oil and aleurone grains, hardly a trace of carbohydrates 
being present. At the onset of germination there is a remark-. 
able appearance of both cane sugar and glucose, which increase 
as the oil diminishes. The old view advanced to explain this 
fact has been the transformation of the oil directly into the 
sugars or one of them, a theory which it was difficult to recon- 
cile with the chemical possibilities of oil. I have found that 
side by side with the appearance of the sugar we have also the 
formation of a considerable quantity of lecithin, a fatty body con- 
taining nitrogenand phosphorus. The seed containsa compara- 
tively large amount of phosphorus in the form of the well-known 
globoids of the aleurone grain, a double phosphate of calcium 
and magnesium, The occurrence of this body points to a con- 
siderable interaction of various substances existing in the seeds, 
the phosphorus apparently coming from the globoids and the 
nitrogen from the proteids. Instead, therefore, of the fat being 
transformed into sugar, it seems certain that a very considerable 
metabolism is set up, in which the very constituents of the 
endosperm interact very freely together. [am informed by Mr. 
Biffin, who has investigated the histological changes accompany- 
ing the germination, that the protoplasm of the endosperm cells 
appears to increase in amount very greatly during the early 
stages. The observations suggest a very vigorous resumption of 
metabolic activity by the cells of the endosperm, in the course 
of which the various reserves are brought into relation with the 
living substance of the cells and a number of new products are 
formed to minister to the nutrition of the growing embryo. The 
formation of the sugars may more probably be referred to the 
renewed activity of the protoplasm of the parent gametophyte 
than to a direct transformation of the fat under the influence of 
the embryo. Further researches upon a large variety of seeds 
appear necessary to give us a true idea of the chemical pro- 
cesses of germination. What now appears probable in the case of 
fatty seeds may prove to be truealso in the case of those which 
have other varieties of reserve material. 
Thave already alluded to the problems concerning the electrical 
phenomena presented by the plant at rest and during activity. 
Very little work has so far been done in this direction, and our 
knowledge of the subject is materially less than that concerning 
similar phenomena in muscle and nerve. Still a beginning has 
been made, and we have observations on record due to Waller 
and to Bose which are of the greatest interest, not only because 
they show agreat correspondence in behaviour between animal 
and vegetable structures, but on account of their possible im- 
portance in determining the character of many of the metabolic 
processes and the forces at work in the tissues, 
Some very striking results were only a few months ago pub- 
lished by Bose on the electric response in ordinary plants to 
mechanical stimulation. He arranged a piece of vegetable sub- 
stance, such as the petiole of the horse-chestnut, or the root of 
a carrot or a radish, so that it was connected with a galvano- 
meter by two non-polarisable electrodes. The uninjured tissue 
gave little or no evidence of the existence of electrical currents ; 
but if a small area of its surface was killed by a burn or the 
application of a few drops of strong potash, a current was ob- 
served to flow in the stalk from the injured to the uninjured 
area, just as isthe casein animal tissue. The potential difference 
in a typical experiment amounted to 0°12 volt. The tissue was 
then stimulated, either by tapping or by a torsion through a 
certain angle, and at once a negative variation or current of 
action was indicated, the potential difference being decreased by 
0'026 volt. Very soon after the cessation of the stimulus, the 
NO. 1719, VOL. 66] 
NATURE 
[OctoBER 9, 1902 
tissue recovered and the current of rest flowed as before. Bose’s 
investigations extended considerably beyond this point, and! 
established a very close similarity in behaviour between the 
vegetable substance and the nerves of animals. Summation 
effects were observed, and fatigue effects demonstrated, while it 
was definitely shown that the responses were physiological, 
They ceased entirely as soon as the piece of tissue was killed by 
heating. 
This remarkable demonstration of similar electrical properties 
to those possessed by nerve strengthens very greatly the view 
of the conduction of stimuli in the plant by means of the proto- 
plasmic threads which have been demonstrated by Gardiner and 
others to exist throughout the plant, uniting cell to cell into one 
coherent whole. 
Much remains to be done in this field; indeed, not more than 
a beginning has been made. The electrical accompaniments to 
response to stimuli have been investigated by Burdon Sandersom 
in the case of Dionza, but many other instances are stilk 
awaiting examination. The peculiar phenomena of electrotonus. 
and their relation to stimulus have so far only been observed in 
animals. 
These observations strengthen considerably the view of the 
identical nature of animal and vegetable protoplasm which has 
in recent years come into prominence, and which is receiving, 
more and more support in all directions. ie 
These electrical currents, following mechanical action, which 
no doubt is accompanied by chemical change, make us ask 
whether electrical phenomena do not in all probability accom- 
pany the slow chemical actions which we call metabolism, The 
view that electrical energy is concerned in the processes of 
photosynthesis, suggested in an earlier part of this Address, is 
certainly not weakened by a consideration of these phenomena. 
The probability of the transmission of stimuli through 
vegetable tissue along the protoplasmic threads, extending from 
cell to cell, has been supported during the last year or two by 
some remarkable observations claimed to have been made by 
Nemec on certain roots and other organs. He says he has suc- 
ceeded in demonstrating a continuous fibrillar structure in the 
protoplasm of the cells, fibrils passing along it in a longitudinal 
direction and apparently connecting the protoplasm of a longi- 
tudinal series of cells into a conducting chain. These con- 
ducting strands extend between the sensitive region—e.g. the 
tip of the root—and the region which is growing, and which is. 
caused by the stimulus to curve. Nemec says that these con- 
ducting strands can be made evident by the use of appropriate 
staining reagents. They vary in number and position, but 
appear to be confined to sensitive and motile organs. 
It is clear that the matter cannot rest where it is. The state- 
ments made by Nemec call for investigation by both histologicab 
and physiological methods. It is possible that appropriate 
reagents may lead to the recognition of structure in what has. 
been hitherto regarded as undifferentiated protoplasm. 
Before concluding this Address I may call attention to the 
vast field opening up in connection with the pathology of 
plants. The work done by our predecessors has been more 
largely work on the morphological peculiarities of various fung? 
than upon the physiological changes which constitute pathology, 
properly so called. It is only recently that attention has been 
given to the broad questions of disease in plants. Even now, 
however, certain advances have been made, andthe direction of 
research is taking shape. In the science of pathology, little in 
recent years has been so fascinating as the question of immunity 
against the attacks of certain diseases, either hexeditary oF 
acquired. It has been bound up with the very large question of 
toxins and their attenuation, their opposites, the antitoxins an@ 
matters of a similar nature. Ide 
Great results have been obtained in human pathology, with 
which it is not for me to deal. I mention them here because 
we are face to face with the possibility of treating some of the 
diseases of plants in a similar way, and perhaps on the thresh- 
old of very far-reaching discoveries. 
I may call attention to the discoveries of Ray and of Beauverie 
upon the general question of plant infection and especially 
upon a disease set up by a fungus known as Sotrytis cinerea, 
which attacks grapes, begonias and other plants. The fungus 
exists in three forms, one of which is a harmless saprophyte, 
another a destructive parasite and a third intermediate between 
the two. The first is a very common fungus, developing on 
decaying plants and bearing ordinary gonidia or spores. The 
second is completely filamentous and bears no reproductive 
