1 45 
Spore Formation in Torreya californica. 
mother-cell into three cells only. In the case of Sequoia seni- 
pervirens , Lawson 1 has only been able to observe a single division, 
although Shaw 2 had previously stated that four spores occurred in 
this species. Torreya californica resembles the nearly related Taxus 
baccata , 3 as well as Lari.x sibirica 4 and Pinus Laricio 5 in the fact that 
the megaspore mother-cells give rise to four spores of which the 
lowest undergoes further development and is the functional embryo 
sac. 
Iu one ovule, collected oh July 6th of this year, I have observed 
two prothalli, which appear to have been formed from different 
mother-cells. This is the only case I have so far seen in which 
there was any sign of the existence of more than one mother-cell. 
VII.— Summary. 
(a.) Microspore Development. 
The male cones of Torreya californica pass the winter in the 
mother-cell condition. The synapsis state is found about three 
months before it occurs in the embryo-sac mother-cell. Starch is 
absent in the mother-cells through the winter, but appears when 
the nucleus is preparing for the reduction division, and does not 
disappear again until the pollen grains become bi-nucleate. 
No prothallial-cells are cut off, and it s suggested that when 
such cells occur in the pollen grains of the higher gymnosperms, 
their survival is correlated with the presence of bladders in the 
exine, which favour wind transference. In cases such as Torreya 
where no bladders have been developed, it is supposed that the loss 
of the vestigial prothallus has been brought about to secure 
lightness of flight. 
(b.) Megaspore Development. 
The ovules with nucellus and integument already differentiated 
are found in the winter buds. By the end of April the integument 
has over-topped the nucellus, and the arillus begins to appear. The 
embryo-sac mother cell is first distinguishable in the latter half of 
May. A well-marked synapsis stage precedes the reduction 
1 loc. cit. 
2 W. R. Shaw. Contribution to the Life-history of Sequoia sem- 
pervirens. Bot. Gaz. XXL, p. 332. 
3 E. Strasburger. Anlage des Enibryosackes und Prothallium- 
bildung bei der Eibe. Festschrift zur siebzigten Geburtstage 
von Ernst Haeckel. Jena 1904. Reviewed, Bot. Gaz., June, 
1904. 
4 Juel. loc. cit. 
s Coulter and Chamberlain, loc. cit. 
