NovEMBER 5, 1896] 
INA LORE 
2431 
spores occurs, and in others these are replaced by non-motile 
spores. In this case, as in others, it is easy to observe that a 
true difference between the so-called cell division and free cell 
formation (Al. Braun) does not exist; the latter being only the 
result of an early or late dissolution of the septa. 
The homology of the sexuality of Co/eochete with the Arche- 
goniate is only apparent. In none of the green algze (Euch/oro- 
piycee) can an archegonium or antheridium be recognised. The 
genus Aphanochete clearly shows that the affinity of Coleochete 
is with the Chlorophycee, and not with the Archegoniate. A 
fuller account of Prof. Chodat’s paper is to appear in the dzna/s 
of Botany. 
Prof. Zacharias, of Hamburg, gave an account of his researches 
on the histology of the blue-green algze. In each cell there is a 
central colourless portion surrounded by protoplasm containing 
colouring matter. The protoplasm, when treated with reagents, 
reveals a spongy structure. In the surface, or occasionally out- 
side the central portion, there occur granules which agree in 
certain reactions with the chromatin of the nucleus of other 
organisms. To these granules Zacharias has given the name of 
‘central substance.” More recent investigations have made it 
doubtful whether the central substance contains nuclein like the 
chromosomes. It is probable that the central body of the spore 
contains glycogen. In the cell protoplasm there occur granules 
different from the central substance. Cell-division occurs with- 
out the karyokinetic figures. 
PTERIDOPHYTA, XC. 
A paper of exceptional importance was read by Mr. Lang, 
on some peculiar cases of apogamous reproduction in ferns. 
In order to ascertain to what extent apogamy in Nephrodinm 
filix-mas, Desv., is correlated with the cresting of the fern plant, 
from which the spores were derived, the author made cultures of | 
normal and crested forms. Of the three cultures of normal forms 
one was unsuccessful; one of the others was exclusively 
apogamous, while the other reproduced itself in the ordinary 
way. Seven crested varieties were sown; five of these were 
apogamous, and the other two normal. 
Cultures were also made of crested varieties of other species. 
In all in which young plants were produced their development 
was at first normal. After the cultures had continued for nine 
months young plants, developed apogamously, were found in 
Scolopendrium vulgare, Athyrium filix femina, and Aspidium 
aculeatum, var. angulare. 
Unfertilised prothalli of Scolopendrium vulgare formed a 
cylindrical, fleshy prolongation of the midrib, the tip of which 
became in time covered with ramenta, and was continued directly 
as the axis of the young sporophyte. Archegonia were present 
just below the ramenta. 
In some prothalli of a fern from Mr. Druery’s collection, 
which was labelled Lasty@a dilatata, var. cristato-gractlis, a 
similar prolongation of the median region was found. Upon 
this sporangia were borne, sometimes singly, in other cases 
grouped together so as to resemble a sorus. The sporangia had 
a well-developed annulus, which sometimes showed the 
characteristic reddish-brown thickenings of the wall. The pro- 
longation on which the sporangia were situated bore archegonia 
and antheridia, which sometimes intervened between two groups 
of sporangia. Its prothallial nature was, therefore, beyond 
doubt. The sporangia were borne on prothalli on which no 
trace of a young sporophyte could be detected. 
Prof. Bower, F.R.S., contributed a paper on the enumera- 
tion of spore mother-cells and spores as a basis of comparison 
of ferns. The author brought out, in a striking manner, some 
interesting points of comparison between different fern types. 
He gave in a tabular form the results of computation of the | 
number of spores per sporangium in representatives of various 
ferns, and also of sporangia and spores per sorus. These 
brought out distinctly the fact that the potential output per 
sporangium, as estimated by the number of spore-mother cells, 
varies very greatly among Leptosporangiate ferns, being only 
16 in Ceratopteris, while in Gletchenta the number may be 
about 1400 ; Aveta and Osmunda showing, respectively, about 
128, and over 500, The further fact that G/etchenta produces 
an output virtually equivalent to that of AvzzgZoplerzs, is specially 
interesting as showing that no numerical gulf lies between the 
Leptosporangiate and Eusporangiate ferns. 
Remarks were also made on the parallelism of complexity of 
sporangia and antheridia in various homosporous Pteridophyta. 
After the papers by Prof. Chodat, Prof. Bower, and Mr. Lang 
NO. 1410, VOL. 55] 
had been read, a discussion took place, which had special reference 
to the general question of alternation of generations in plants, 
which had been treated at some length by Dr. Scott in his open- 
ing address. In reply to arguments advanced by Dr. Scott, and 
relating especially to the examples of apogamy described by 
Mr. Lang, Prof. Bower expressed the opinion afresh that both 
apogamy and apospory are to be looked upon as abnormalities, 
which are not a proper subject for strict morphological argu- 
ment ; moreover, both are susceptible of a physiological ex- 
planation, as substitutionary growths. The argument from 
apospory, as evidence of homologous alternation, involves the 
fallacy that parts which, under unusual circumstances, can be 
induced to undergo similar development are of similar origin. 
If such abnormalities as Mr. Lang describes be used for 
argument, the complete jumble of succession would allow of 
almost any view. The opinion was expressed by Prof. Bower, 
on the general question, that neither by the description of these 
abnormalities, nor by the other arguments advanced by Dr. 
Scott, is the case for homologous alternation made out. The 
green algze can at most be used as examples of how alternation 
may have originated. 
Dr. Scott then replied to Prof. Bower's criticisms. 
HIGHER PLANTS ; PHystoLocy, ANATomy, &c. 
Prof. Casimir de Candolle, of Geneva, contributed some ex- 
ceedingly interesting notes on latent life in seeds. The author 
gave an account of some experiments, recently carried out, on 
the power of germination of seeds exposed for different periods 
to a low temperature. He also recorded striking instances of 
the development of normal seedlings from seeds which had 
been kept for a great number of years. Robert Brown 
obtained perfect seedlings from seeds of WMelumbium spectosunt 
more than a century old. Plants buried under rubbish 
heaps collected by the Greeks, have been found to develop 
and bear flowers from seeds which must have been at least 
fifteen hundred years old. To test the condition of a dormant 
seed, M. de Candolle exposed the seeds of several plants to a 
temperature too low to admit of the continuance of the process 
of respiration. Seeds of corn, oats, fennel, AZ¢émosa pudica, 
and Gloxinia, &c., were exposed for 118 days to a temperature 
of 40° F. below zero. The experiments were carried on at 
Liverpool in refrigerating machines, in which during eight hours 
each day the average temperature recorded was — 40° F., and 
occasionally far lower. Nearly all the seeds of corn, oat, fennel, 
and a great many of the A/zmosa seeds germinated. The con- 
clusion to be drawn from the experiments seems to be, that in 
resting seeds the protoplasm is not actually living, but has 
reached a stage of inaction in which, although not dead, it is 
endowed with potential life. In other words, protoplasm in 
resting seeds is not analogous to a smouldering fire, but rather 
to those chemical mixtures made up of bodies capable of com- 
bining under certain conditions of temperature and illumination. 
Prof. Marshall Ward, Dr. Scott, and others discussed several 
important points suggested by Prof. de Candolle’s paper. 
Prof. Trail, F.R.S., gave some account of his recent ob- 
servations on the floral deviations in some species of Polygonum. 
The genus has long been known to show considerable departures 
from the arrangement and number of parts accepted as most 
typical (Per. 5. St. 5 + 3, C. 3), such as is found in P. 
convolvulus. a 
A comparison of different species shows that while each 
varies, so as in the more variable species to cover almost the 
whole range observed in the genus, each shows a tendency to 
certain lines of variation. These tendencies are more alike 
usually in the more nearly allied species, so as to correspond 
in the main with the groups based on habit, and they lead from 
group to group. 
The modes of variation commonly observed include almost 
all the recognised modes of departure from floral symmetry. 
They affect all the whorls. The fevzanth in some species is 
very constant. In others it habitually shows cohesion of two or 
more segments, or abortion in different degrees, or suppression 
of one or two (usually the inner) segments. Chorisis of a segment 
is less frequent. Enations from one or more segments are 
frequent in certain species, rare or absent in others. The owter 
stamens often show cohesion of the two in each pair, varying 
from the slightest union of the bases of the filaments to absolute 
union of even the anthers. Abortion (in all degrees to complete 
suppression) of one or more stamens is not rare. The zzer 
stamens seldom show cohesion (except in azvrcz/are and its 
