i 9 09) CHAMBERLAIN— SPERMATOGENESIS IN DIOON 229 



number 



300, the 



* _ 



usual number in Ceratozamia mexicana is 250 to 300, and in Stangeria 

 paradoxa, about 260. In both Ceratozamia and Stangeria the sporan- 

 gia are very small. 



If this is a reduction series, as we believe it is, Microcycas, so far 

 as this character is concerned, has scant claim to the position of 



primitive 



female 



Angela 



from primitive. As far as micro- 



sporophylls and microsporangia are concerned, Dioon is nearer the 

 Cycas condition than any other western cycad. 



The output of spores is very easily estimated. Bower's studies 

 on spore-producing members have shown that the more primitive 

 ferns have a large output, which is gradually reduced as we pass to 



forms. We 



cycads. The output in Dioon edule is about 30,000 spores per spo- 

 rangium. According to Miss Grace Smith (8) the output in EncepJia- 

 krtos villosus is 26,000, in Ceratozamia mexicana 8000, and in Zamia 

 ioridana 500 to 600. It would be interestii _ 

 other cycads. I should expect an output of 30,000 or more in Cycas, 

 and should be surprised if the output in Microcycas reached 20,000. 

 Judging from Cattiw^tt'c (rC\ «™„r,f T should look for an output 



know 



In our study of the spore coats, I looked for the third coat described 

 by Ferguson (4) . The fact that only an intine and an exine are 

 Present in Dioon led me to reexamine Pinus Laricio. I found only 

 a n exine and an intine, as in Dioon, the third coat described by Miss 

 Ferguson (4) being merely the usual intine which her excellent 

 tannic had sharply differentiated from the exine. As preparations 



a third uiax gro^ 



hich she mistake 



— '««-i giuws, out 10 iorm me ponen wuc. ( , 



The blepharoplast in Dioon edule is probably of nuclear origin. 

 1*010 (!) was inclined to believe that the blepharoplasts of Cycas 



from the nucleus, although when first recognizaDie m 



small bodies just outside the nuclear membrane. Webber (: 



toads tw ,v ^__, originate de novo in the cyt 



"" uuuies just outside the nuc 

 5 that in Zamia the blepharoplast 



