92 



MORPHOLOGY OF ANGIOSPERMS 



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61 



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fc 



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u 



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synergids may not always divide. In the same category Casu- 

 arina, as reported by Treub, 25 has long been included ; but a 

 recent study of the genus by Frye 119 has shown that the usual 



three micropylar nuclei occur. Fischer 6 

 reports the occurrence of two eggs in 

 Gomphrcna, which Strasburger suggests 

 may have come from division of the nor- 

 mal egg. 



In Loranthus and Casuarina Treub 

 also states that there are no antipodals ; 

 but Frye's 119 recent investigation of the 

 latter form has resulted in the discovery 

 of three antipodals, which occur either 

 at the chalazal extremity of the expand- 

 ed portion of the sac, or in the tubular 

 haustorial elongation. 



In Helosis guayanensis (Balanopho- 

 raceae) Chodat and Bernard 83 state that 

 the primary antipodal nucleus (binu- 

 cleate stage) rarely divides, but soon de- 

 generates, which means also the absence 

 of an antipodal polar nucleus (Fig. 40). 

 The same phenomenon has been ob- 

 served by Hall 109 in Limnocharis, the 

 primary antipodal nucleus remaining 

 undivided. Several cases have also been 

 reported in which regularly formed po- 

 lar nuclei approach one another but do 

 not fuse before endosperm formation, as 

 in Balanophora elongata (Treub 32 ), 

 confirmed also in B. indica by Van Tie- 

 ghem, 45 and in B. globosa by Lotsy 69 ; 

 but in the allied Bhopalocnemis (Lot- 

 sy s2 ) the polar nuclei fuse. In the or- 

 chid Gymnadenia also, Marshall-\Yar<l ' 

 states that the polar nuclei do not fuse; 

 in the parthenogenetic Antennaria alpina Tuel 57 (Fig. 41) ob- 

 served the same phenomenon ; in Lemna Caldwell 62 reports that 

 the polar nuclei often do nol fuse; ami in Juglans nigra Kar- 

 sten 115 states that there is probably no fusion of polar nuclei, or 



to 



Fig. 41. — Antennaria alpina. 

 Egar-cell much extended 

 and polar nuclei about to 

 divide ; a, antipodal cells; 

 «, egg ; p, polar nuclei ; s, 

 synergid ; m, micropyle ; 

 x 250.— After Juel.™ 



