728 THE AMERICAX XA I i RA T. I N tM.. XXXVIII. 



spindle-" to form at once four daui^htcr nuclei. These events 

 arc unparalleled, as far as the writer is aware, in the jilant or 

 animal kin-^dom, and C()nsec[uently the account de>er\es especial 

 attention. A four-rayed tii;ure around luicleus is not surpris- 

 in<^ hecause the spore' mother-cell of tlie J un-ennanniales is four 

 lobed, and its centrally placed nucleus lies in a restricted area. 

 But the simultaneous distribution of C|iadrui)led chromosomes 

 to form four daughter nuclei is a process wliose esiablisliment 

 .would be of fundamental significance, b'armer also described a 

 centrosome at each pole of the " quadri|)olar si)indle.'" 



Farmer ('95^7, and r) followed his pai)er on Tallax icMnia with 

 studies on other liverworts. He reixtrled the (juadripolar 

 spindle" in the early stages ot mitosis m several of the Junger- 

 manniales, but did not find the quadrupling and simultaneous 

 distribution of the chromosomes as in Palku icinia. The quad- 

 ripolar spindle" when present was a temporai-y structure re])laced 

 later by the bipolar spindles of two successive mitoses with a 

 longer or shorter interval between. b^irmer considers the 



quadripolar spindle" of these forms as transitional between 

 that of Pallavicinia and the normal bipolar spindle. The Ric- 

 ciales. Marchantiale^ and Anthocerotales present two successive 



The writer has described thccNentsol spnrogenesi. in I'cllia 

 (one of the Jungermanniales) in a papt-r covering the nuclear 

 activities at .several [)eriods in its life history (Davis, :oi), and 

 confirmed much of Farmer's account of the mitoses in this spore 

 mother-cell. These are two in number and successive, with a 

 very well defined resting period betwx>en the first and the second. 

 There is a four-rayed figure })resent during the i)rophase of the 

 first mitosis, and 'this seems to oh , c-pond to barmer's " quad- 

 ripolar spindle." The nucleus lying in the center .)f the tour 



sheath which develops a fibrillar structure. ' Many of these 

 fibrillae extend int.. the lobes of the spore mother-cell because 

 the nucleus is conlined to a narrow space in the constricted cen- 

 tral region of the cell and the lobes offer the only {x.ssible relief 

 for the crowded conditions. J I()wever,;_the four-rayed structure- 

 is not present when the chromosomes are ready for distribution, 



