358 BOTANICAL GAZETTE [may 



Microsporangium. — The staminate cones are long and slender 

 and very symmetrical. They vary greatly in size, those growing 

 on the dry grass veldt sometimes being as short as 8-9 cm. in 

 length, while those in the shaded bush veldt may reach a length 

 of 20cm., exclusive of the stalk, which may be more than 5cm. 

 in length. The sporophylls are small and the number of sporangia 

 averages only about 150, which is lower than in any cycad except 

 Bowenia and Zamia. 



We have already stated that Stangeria was originally described 

 as a fern, because the leaves so strikingly resemble those of Lomaria. 

 The microsporangia are equally fernlike and bear a particularly 

 close resemblance to those of Angioptcris. The wall of the micro- 

 sporangium consists of an outer layer of very thick-walled cells, 

 a very scanty tapetum, and 3-5 intervening wall layers. The 

 thickening of the outer cells is most pronounced at the base, dimin- 

 ishes gradually on the sides, and at the top becomes so thin that 

 it easily breaks, forming a pore through which the dense cell con- 

 tents escape shortly before the dehiscence of the sporangium. 



The earlier stages in the development of the microsporangium 

 and in the origin and development of sporogenous tissue have been 

 so thoroughly described and illustrated by Lang (2) that we have 

 not felt it necessary to deal with this phase of the subject; but 

 on account of the peculiar or at least newly described behavior 

 of the chromatin at fertilization, the reduction divisions in the 

 pollen mother cells would have been studied if material in this 

 stage had been available. 



Gametophytes 



Male gametophyte. — The microspore is formed before any o\ 

 the wall cells of the microsporangium begin to break down, but 

 before the nucleus of the microspore divides the wall cells begin 

 to disorganize and the tapetum becomes almost indistinguishable. 

 During the two mitoses which result in the formation of prothallial 

 cell, generative cell, and tube cell, the tapetum and the wall cells, 

 with the exception of the hard outer layer, break down and form a 

 dry, homogeneous membrane about the pollen grains, holding them 

 together in one spherical mass. At the time of dehiscence, the 



