268 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



the protoplasm beginning at tlie center of the mother-cell and 

 proceeding outward. Hofmeister (32b), however, noted that 

 there was successive bipartition and that a plate of granules, or 

 sometimes a ring of granules at the equator preceded the centrip- 

 etal development of the partition wall. Strasburger (67a), 

 describing the same species, says that there are irregular masses 

 of material heaped up in tHe equatorial plane. He describes the 

 division as quadripartition by cell-plates, the position of the nuclei 

 being either tetrahedral or monoplanal. The mother-cell-wall is 

 reported to swell when placed in a glycerine solution. His figures 

 (67^) are not entirely convincing that there is a plate and not a 

 row of granules across the equator, and they do not demonstrate 

 a centrifugal partition. In Psilotum he (67a) also shows an equa- 

 torial accumulation of material at the time of the two successive 

 divisions. In the same form Hofmeister (326) reports monoplanal 

 quadripartition and mentions a girdle of granules about the equator 

 "ohne dass das Auftreten einer solchen Scheidewand vorausginge." 

 In Isoetes Strasburger (67a) reports tetrahedral quadripartition 

 by cell-plates, the fibers crossing and swelling at the equator. 

 In Marsilea Russow (58) reported tetrahedral quadripartition; 

 and more recently Strasburger (67^) has published quite an ex- 

 tensive paper on Marsilea in which he reports quadripartition in 

 both the macrospore and microspore formation. His figures show 

 both a monoplanal and a tetrahedral arrangement of the nuclei 

 in the metaphases of the homoeotypic division. The microspore- 

 mothcr-wall is shown in the figures to be thickened, but no thick- 

 enings of the fibers are shown. Strasburger (67</) has also re- 

 ported quadripartition in Lycopodium. 



h. Quadripartition in gymnosperms 

 In the cycads also the mother-wall thickens during the reduction 

 divisions. In this group, however, division into spores is accom- 

 plished by two successive bipartitlons. The nuclei may lie either 

 in one plane or in a tetrad, as described by Juranyi (36) for Ccrato- 

 zamia. His figures of the first division show constriction fur- 

 rows accomjjanied by thickening of the mother-wall. Stages in 

 the second division are not figured. Treub found rather obscure 

 cell-plates in the first division of Zamia {75b). 



In the larch, as noted al)o\e, Tim])C'rlake has reported both 



