282 Lawson . — The Gametophytes and Embryo of the 
(’03, ’05) investigations on the anatomy of the vascular system. Indeed, in 
any scheme which may be advanced concerning the phylogeny of this 
ancient group, the sporophyte as well as the gametophytes must constitute 
an essential part, for it is mainly from the point of view of anatomy that we 
can hope to correlate the evidence from the fossils — the structures associated 
with the sexual generation being so much more perishable. 
In this series of studies no attempt has been made to follow any natural 
sequence in the types selected. It was thought that good results might be 
obtained by working up the available material first ; leaving the more 
inaccessible and perhaps more interesting types, such as Araucaria and 
Agatkis , for future investigations. The present paper is merely intended as 
an addition to the knowledge which we have already received from the 
works of Strasburger (79), Arnoldi (’01), Land (’02), Coker (’03), and the 
present writer (’04) on the gametophytes of the Cupressineae. Special 
attention has been given to Libocedrus , because, up to the present, no 
observations have been recorded concerning the sexual generation of this 
genus. The work was commenced in the Laboratory of Stanford Univer- 
sity, California, but most of it was carried on in the Jodrell Laboratory, 
Kew Gardens. To Lieut.-Col. Prain, C.I.E., F.R.S., Director of the Royal 
Gardens, Kew, and to Dr. D. H. Scott I wish to express my sincere thanks 
for extending to me the privileges of the Laboratory. My thanks are also 
due to Mr. L. A. Boodle, F.L.S., whose constant attention and many 
kindnesses aided materially towards the completion of the work. 
Material and Methods. 
The collection of material for this investigation was commenced in 
March, 1903, and was continued at short intervals as time permitted. 
The collections extended over a period of two years. All of the material 
was obtained from trees growing in the arboretum of Stanford University. 
The Cupressineae are here richly represented in both genera and species, 
and the climatic conditions seem very favourable for the development and 
maturing of the fruit. Every year there is an abundance of cones on most 
of the trees. 
The methods used are the same as those which I adopted in previous 
investigations on the Conifers (Lawson ’04), and gave satisfactory results. 
The Male Gametophyte. 
In Libocedrtis decurrens pollination takes place during the last week in 
March and early in April ; the period extending from two to three weeks. 
The first collections of the microsporangia were taken early in March, and 
at this time the pollen seemed fully developed — each grain having a thick 
exine and containing two nuclei, the latter being separated from each 
other by a distinct membrane. In the division of the spore before its 
