1 8 E antes.- — The Morphology of Agathis attsfralis. 
does their arrangement suggest an origin from two primary cells — rather 
that each is itself an original cell of the prothallus. Thus, if the two pro- 
thallial cells of most of our Conifers are a reduction from an oricnnal 
o 
complex, wherever a larger number occurs the mode of origin at least 
seems recent. There would seem to be in the extensive running and 
branching tubes of Agathis a demand for a considerable supply of nuclei. 
The derivation of these would be most naturally from pre-existing pro- 
thallial nuclei. Thus the evidence seems to favour the belief that the tissue 
in question is cenogenetic and not palingenetic. 
Another feature of palaeozoic seeds which it has been suggested the 
Araucarians have retained is the great freedom of the nucellus from the 
integuments. This condition has been demonstrated above for Agathis . 
However, no systematic significance can be attached to this character, since 
Fujii ( 2 ) has recently shown it to be very variable even within a genus. 
Complete freedom of the nucellus exists in scattered genera among the 
Coniferae — Callitris , Araucaria , Cunninghamia , Juniperus. 
The large number of archegonia and their scattered positions are 
suggestive of some lower forms. Bui: the archegonia of the heterosporous 
Pteridophytes are few and terminal. In the Cycadofilicales and the 
Cordaitales very little is known of the archegonia, but they were apical 
(beneath the pollen chamber) and surely not numerous. Ginkgo has two or 
three terminal archegonia. The number in the Cycads, with the exception 
of Microcycas, is ten at the most. Among the Conifers the large numbers 
are found in the recent tribes — as many as 60 in the Taxodineae and 
ioo in the Cupressineae. To be sure many of these are found in complexes, 
but Agathis shows how many scattered archegonia may be brought together. 
And the parallelism with Sequoia must be emphasized again. This genus 
also has many irregularly placed archegonia, and some are deep-seated. 
Further, in both genera there are the same transitions between a single 
archegonium and a complex. Thus the few terminal archegonia of the 
Abietineae seem more likely to be primitive, and specialization to have 
taken the form of multiplication. 
The haustorial nature of the pollen-tubes far exceeds that of any others 
known. That the cone axis and its bundles, even the xylem, should be 
invaded is remarkable indeed. A cause for such behaviour cannot now be 
suggested ; far too little is known of the early history of the tubes. But 
there is the probable reason for the germination of the pollen on the cone 
scales, that no micropyle is ready to receive it. The seeds of the lower 
Gymnosperms have given no evidence of pollen-tubes. In the Cycads, 
though, the haustorial nature of the pollen-tubes is well known. But the 
section which is concerned with carrying the fertile elements is not at all 
extensive and can hardly be compared with like portions in Araucaria and 
Agathis, If comparisons are to be made of any feature of this so-called 
