258 



THE AMERICAN NATURALIST 



[Vol. XL 



were inaccurate and Ins earlier conclusions wron*?. Strasburger 

 \\ion<rl\ nitei|)i(t((l tli( (liMnk<;Mtin<r cells at the base of the pollen 

 gram as mere slits m the wall having an origin similar to that of the 

 wmgs of the gram (72, p. 127). .Scliacht ("00) had interpreted 

 these correctly as also had Meven ('39). Following Ilofmeister's- 

 suggestion htrasl)urger said that the cells formed in the interior 

 of the pollen grain could onlv be considered vegetative cells, 

 homologous to the prothallium of the fern. He supposed the large 

 cell ot the pollen grain corresponded to an antheridium, believing 

 that It furnished the male gametes. lie also thought that the cell 

 structure was the same m Pinus, Podocarpus, and Cupressus 

 (72, p. 130). Later investigations have shown that no two of 

 these are exactly alike. On page 131 .Strasburger (72) remarks 

 that the number of cells which are formed bv division in the pollen 

 grain in Cycads and Conifene remains constant. It never exceeds 

 two, according to his observations. The report of a larger number 

 can only be founded on the view that the split jn the wall is a disin- 

 tegrated cell. 



In a paper published ni is?."), rscliistiakofl- wrote that where 

 there are several small cells, tlicv aiise h>/ surrrssi rr dirl-sion of 

 the large polim nil as m Larix. or the second cell can divide to 

 form i^^o cells as in (.inkgo ( 7"), p 100) In Pmus ac(oidmg to 

 Tschistuikod tuo, or at the most three small cells arise The 

 one or two hrst cells arise l)v a real division of the larL'e |)ollen 

 cell. The small cells mav have their whole volume in the intine 

 The third large cell, archino- into the j.ollcn grain arises bv divi- 

 sion of a small cell. In Abies the third cell forms bv free cell 

 formation, tins divides into two. ra<-li of tlit's(> can divide au'ain, 

 an.ltlHM >MoMl.n (<IU( mmIivmI. lon^iindin .IK o. tian.\erseh 

 Th( m,m1I(.I! m, o,.,1Iu, < n.i.kcu, , div.d, 



iii"iJi .1,,. ot tli< ol,M]\ ,t.on. ni.d, In ^iMln.tiakoff ^^ere 



were not proNcd, namely, that several small cells were cut off 

 suc{-e»i\. i\ troni rlic large pollen cell in such grains as those of 

 Laiix .ti.l Pun., .nd that the last one of the row of cells forme.l, 

 became the progenitor ot sj)ermatozoid mother cells. Mis article 

 also m.ntion^ \ imtion> in rlu iHothallium ot Vbies, and m the 

 number ot cells formed in 1 hnja, where he says there mav be two 



