LYCOPODINEM 



525 



velop in the late summer and autumn, producing at this time 

 only macrosporangia. In the spring the growth of the stro- 

 bilus is resumed, and microsporangia are developed, the game- 

 tophytes produced from the macrospores of the previous year 

 being fertilised by spermatozoids developed from the micro- 

 spores developed in the spring. In S. apus there was evidence 

 that the embryos formed in the autumn passed through the 

 winter within the macrospore, completing their development in 

 the spring. 



The leaves arise much in the same way that the branches 

 do, but do not develop a single apical cell. The growth is 



Fig. 304.— Cross-section of a fully-developed stem of 5". Kraussiana, showing the two 

 vascular bundles suspended in the large central lacuna by means of the trabeculse 

 (*), X75; B, a single vascular bundle, X4S0; x, x, scalariform tracheids; s, s, 

 sieve-tubes. 



much the same as in the first leaves of the embryo, and as in 

 these the early growth is due mainly to a row of marginal 

 initial cells from which segments are cut off alternately above 

 and below. 



