20 
NATURE 
{| NovEMBER 5, 1896 
to the necessity of a complete study of the minute structure of 
wood in relation to the modern theories. The concluding words 
of the opening address may be quoted verdatzn :—“‘It is at 
least a hopeful fact for Messrs. Dixon, Joly, and Askenasy that 
we cannot point to anything in the anatomy of wood which is 
absolutely inconsistent with their views. Whether we are friends 
or opponents of Messrs. Dixon, Joly, and Askenasy’s theory, 
the broad facts remain that water has the power of resisting 
tensile stress, and that this fact must henceforth be a factor in 
the problem. There are difficulties in the way of our authors? 
theory, but it is especially deserving of notice that many of these 
difficulties are equally serious in the case of any theory which 
excludes the help of the living elements of the wood, and 
assumes a flow of water in the tracheals. The authors have not 
only suggested a vera cazsa, but have done so without multiply- 
ing difficulties. There is, therefore, a distinct balance in their 
favour. Huxley, quoting from Goethe, makes use of the 
expression ¢hatige Skepszs. It is a frame of mind highly 
appropriate to us in the present juncture, if we interpret it to 
mean a state of doubt whose fruit is activity, and if we translate 
activity by experiment.” 
Prof. Vines, F.R.S., drew attention, in the first place, to a 
paper of his, recently published in the Avzads of Botany, giving 
an account of a number of experiments on the suction-force of 
branches. Je had been under the impression that the results 
obtained were independent of the action of atmospheric pressure 
—that they were solely indications of tensile stress exerted by the 
transpiring branch upon the water in the apparatus ; but now he 
had reason to believe that they were, as a matter of fact, affected 
by the atmospheric pressure. Hence these results are not 
different in kind from those of other observers, but are com- 
parable with them. The apparatus which he employed is, how- 
ever, very useful, on account of its sensitiveness and simplicity, 
for purposes of demonstration. 
The observations in question brought out two important facts : 
(1) that a high suction-force can be developed by branches which 
have been deprived of their leaves ; and (2) that this suction- 
force is not dependent upon the life of the branch. He then 
proceeded to give an account of subsequent observations 
made with dead hazel-branches (pea-sticks), which had been 
found to develop considerable suction-force amounting, in one 
case, to 194 inches of mercury with a stick 18 inches long. He 
concluded by expressing the opinion that, in recent attempts to 
explain the mechanism of the transpiration-current, the part 
played by the ‘‘imbibition” of the cell-walls had been under- 
estimated ; and urged that what was especially requisite for 
further advance, is a more complete investigation of the physical 
properties of a dead piece of stick. 
The second discussion, on some current problems connected 
with cell-division, was opened by Prof. Bretland Farmer, who 
gave a very complete account of the present position of cell- 
division problems, before a joint meeting of Sections C and Kk. 
In reference to the centrosome question, Prof. Farmer spoke as 
follows :— 
‘“* Few people are agreed as to what its (the centrosome) very 
nature actually is, and perhaps still fewer as to the part which 
it playsinthecell. Some regard it as the active agent in bringing 
about nuclear division, whilst others believe it to be a transient 
structure, called into existence by the forces which are at work 
during karyokinesis. The occurrence and behaviour of centro- 
somes during karyokinesis (nutosis) require a comparative treat- 
ment. Whilst it is quite possible that in the cells of some 
organisms, the centrosome may possess a marked individuality, 
it does not therefore necessarily follow that it must occur univer- 
sally, or that it is concerned, as a principal, with the process ; 
and this latter remark applies even to those instances in which 
it appears most prominently.” 
Profs. Minot, Zacharias, Hartog, and others, took part in the 
discussion. An important contribution, bearing directly on this 
subject, was made by Miss Ethel Sargant in a paper entitled 
“On the heterotype divisions of LzZéa Martagon.” Wer work 
may be briefly summarised as follows. There are two series of 
nuclear division in the life-history of Z2/éu MJartagon, which 
exhibit twelve chromosomes in place of twenty-four. The pre- 
parations made by Miss Sargant include the whole odgenetic 
series and the first three divisions of the spermatogenetic series. 
The second and third divisions in both are precisely similar to 
vegetative nuclear divisions except in possessing only half the 
number of chromosomes. They are called hovotyfe. 
The first nuclear division on either side is called helerotyfe, 
NO. 1410, VOL. 55 | 
because the process of karyokinesis ditfers from that of the 
vegetative nucleus. Miss Sargant dealt with the distinguishing 
features of the latter heterotype divisions. 
THALLOPHYTA. 4 
Prof. Magnus, of Berlin, gave an account of some recent 
observations on the Chytridiaceous genus Urophlyctis. The 
author maintained the genus Uyrophlyctzs. He described the 
development of the species Urophiyct’s Kriegeriana, occurring 
in Carum caruz, established by him some years ago, and showed 
that its spores are formed by the conjugation of two cells, arising 
from different filaments, and that the development of the fungus 
takes place within a single cell of the host, namely, the central 
cell of the gall produced by it, which is of limited growth. The 
author proved that the fungus observed by Trabut in Algiers, 
which causes large swellings on beetroots, also belongs to this 
genus Urophlyctzs. Prof. Magnus proved that its spores are 
likewise formed by the conjugation of two cells, arising from 
different filaments, exactly as in Urophiyctis. 
Mr. Vaughan Jennings contributed a note on Coradlorhiza 
zanata, R.Br., and its associated fungi. Without being able to 
speak of his conclusions as in all cases definitely established by 
proof, the author thus summarised his results, 
“* So far, then, as this district (Davos Platz) is concerned, it 
seems that the ‘mycorhiza’ of Corallorhiza is a hymeno- 
mycete, and commonly an agaric; and that certain species of 
Tricholoma and Clitocybe are those commonly observed. The 
only other forms yet noted in proximity to Cor allorhiza are 
Cortinarius subferrugeneus, Batsch., and Mycena umbellifera, 
Sch., but further evidence with regard to these is at present 
wanting.” 
Mr. Vaughan Jennings also gave an account of a form of 
Schizomycetes, for which he proposed the name <Astrobacter 
Jonestz. 
Mr. Coppen Jones contributed some observations on the so- 
called tubercle Aacz//s. He expressed the opinion that there 
are several considerations which tend to modify our views with 
respect to its biological status. The facts he brought forward 
favoured the view that the so-called ‘‘tubercle bacillus” is 
really a stage in the life-history of some higher form of fungus 
with a definite mycelial growth. From a systematic point of 
view, it cannot be regarded as coming within any definition 
of the genus Aacid/us, and it is suggested that a more appro- 
priate name would be Zwdberceulomyces. Whether the change in 
our view as to the real nature of the tubercle fungus will in the 
future be of any diagnostic value it is impossible to say, as 
comparatively few cases showing the filamentous growth have 
yet been observed ; but there is some evidence in support of the 
idea that the hyphal type may be correlated with more chronic 
shes of the disease, where actual tissue destruction is relatively 
slight. 
Mr. W. G. P. Ellis contributed an account of the life-history 
of a fungus which is the cause of a parasitic disease in the 
Liverwort Pella epiphylla. A disease appearing on and spread- 
ing centrifugally over a pan of Pe//éa was investigated during 
the summer of 1896. The author was led to regard the fungus 
as the conidial phase of an Ascomycete, similar to, if not identical 
with Ascotricha, the conidial stage of a Chetomcune. 
Prof. Chodat, of Geneva, communicated an extremely interest- 
ing paper of far-reaching importance on the polymorphism of 
the green alge, and the principles of their evolution. The 
green alge may be divided into two distinct groups, the 
Euchlorophycee, and the Stphonee. In the former a true cell-. 
division takes place, while in the latter the thallus is non-cellular. 
The starting-point in the evolution of the Zuchlorophycee is 
very likely the Padmellacee (including the genera 7etraspora, 
Palmella, and Afpiocystzs). Observations show that no clear 
boundary line can be drawn between the different groups and 
the Palmellacee, from which they are supposed to be derived. 
The Volwoctnee, for example, agree very closely with the 
Palmellacee in the structure of the cells, but in these the resting 
stage is only transient. In this non-motile condition obtained 
by culture, they cannot be distinguished from the latter. In 
another direction the Protococcacee can be derived from the 
Palmeltlacee by the prevalence of the sporangial condition. In 
some species or genera the single-celled sporangium produces 
zoospores, but in the course of evolution these are replaced by 
the non-motile spores, when the mother cells or sporangia have a 
definite form as in Scexodesmus and Raphidium. 
In certain forms of Plewrococcus vulgaris a production of zoo- 
