1004 REPORT—1896. 
such pieces of evidence as militated against their views, and consequently their 
position was insecure so long as these hostile posts were left uncaptured. 
Quite recently the whole question has been reopened by the striking observa- 
tions of Mr. Harper, an American botanist working at Bonn. 
Zopf, in 1890,! pointed out th it up to that time it had not been possible in any 
Ascomycete to demonstrate a true process of fertilisation by strictly scientific 
evidence, namely, by observing the fusion of the nuclei of the male and female 
elements. Exactly the proof demanded has now been afforded by Mr. Harper’s 
observations, for in a simple Ascomycete, Spherotheca castagnet, the parasite 
causing the hop-mildew, he has demonstrated in a manner which appears to be 
conclusive the fusion of the nucleus of the antheridium with that of the ascogo- 
nium.? It is impossible to evade the force of this evidence, for the fungus in 
question is a perfectly typical Ascomycete, though exceptionally simple, in so far as 
only a single ascus is normally produced from the ascogonium. It is unnecessary 
to point out how important it is that Mr. Harper’s observations should be con- 
firmed and extended to other and more complex members of the order. In the 
mean time the few who (unlike your President) had not bowed the knee to Brefeld 
may rejoice ! 
It is impossible to pursue the various questions which press upon one’s mind in 
considering the morphology of the Fungi. The occurrence not only of cell-fusion, 
but of nuclear fusion, apart from any- definite sexual process, now recorded in 
several groups of Fungi, urgently demands further inquiry. Such unions of nuclei 
have been observed in the basidia of Agarics, the teleutospores of Uredinex, and 
even in the asci of the Ascomycetes. That such a fusion is not necessarily, as 
Dangeard * has supposed, of a sexual nature, seems to be proved by the fact that 
it occurs in the young ascus of Spherotheca long after the true act of fertilisation 
has been accomplished. It is possible, however, that these phenomena may throw 
an important side-light on the significance of the sexual act itself. 
Another question which is obviously opened up by the new results is that of 
the homologies of the ascus. The observations of Lagerheim + on Dipodascus point 
to the sexual origin of a many-spored sporangium not definitely characterised as 
an ascus, On the other hand, not only sporangia, but true asci are known to arise 
in a multitude of cases direct from the mycelium. It is of course possible that as 
regards the asci these are cases of reduction or apogamy ; on the other hand, it is 
not wholly impossible that the asci may turn out to be really homologous with a 
sexual sporangia, even though their development may often have become associated 
with the occurrence of a sexual act. However this may be, there is at present no 
reason to doubt that a very large proportion of the Fungi are, at least functionally, 
sexless plants. 
CHALAZOGAMY. 
Among the most striking results of recent years bearing on the morphology of 
the higher plants, Treub’s discovery of the structure of the ovule and the mode of 
fertilisation in Casuarina must undoubtedly be reckoned. The fact that the 
pollen-tube in this genus does not enter the micropyle, but travels through the 
tissues of the ovary to the chalaza, thus reaching the base of the embryo-sac, was 
remarkable enough in itself, and when considered in connection with the presence 
of a large sporogenous tissue producing numerous embryo-sacs, appeared to justify 
the separation of this order from other angiosperms. Then came the work of Miss 
Benson in England, and of Nawaschin in Russia, showing that these remarkable 
peculiarities are by no means confined to Casuarina, but extend also in various 
modifications to several genera of the Cupuliferze and Ulmacew. They are not, 
however, constant throughout these families, so that we are no longer able to 
attach to these characters the same fundamental systematic importance which 
their first discoverer attributed to them. It is remarkable, however, that these 
‘Die Pilze,’ Schenk’s Handbuch der Botanik, Bd. iv. p. 341. 
Berichte der deutschen bot. Gesellschaft, vol. xiii., January 29, 1896 
Le Botaniste, vols. iv. and v. 
Pringsheim’s Jahrbu *».f. Wiss. Bot. 1892. 
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