330 NINETEENTH REPORT. 



B — Sympetalae 



V. Gentianales Vincetoxicum nigrum. 



Vincetoxicum medium. 



VI. Tubiflorales Sinningia Lindleyana. 



VIII. Campanales Alchemilla pastoralis. 



Alcliemilla sericata. 

 Taraxacum officinalis. 

 C — Monocotyledonae 



I. Panadanales Limnocharis emarginata. 



Naias major. 



IX. Lilliales Allium odorum. 



Erythronium americanum. 

 Erythronium dens-canis. 

 Funkia ovata. 

 Iris sibirica. 

 Lillium martagon. 

 Nothosc'ordon fragrans. 

 Tulipa Gt'sneriana. 



XI. Orchidales Coelo(bo)gyne ilicifolia. 



Gymndenia conopsea. 



Dr. Coulter in a recent letter states: "I know of no record of poly- 

 embryony in the Archichlamydeae since the date of the Angiosperm 

 volume." It would thus seem probable that these thirty-six cases scat- 

 tered through fifteen of the forty-nine Alliances gives a fair rei3resenta- 

 tion of our knowledge of the occurrence of polyembryony in the Angio- 

 sperms. It is to be noted, however, that, in the words of Coulter^ "the 

 cases on record are already so numerous that only an exhaustive study 

 of the literature would make it safe to venture an estimate of the number. 

 Since in nearly all the cases described this phenomenon is rare rather 

 than habitual, it is probable that under conditions not yet understood a 

 large number of plants may exhibit polyembryony occasionally." 



This new case of polyembryony came to my notice in a collection of 

 germinating acorns brought into the laboratory for class use in the 

 spring of 1910. Among them one acorn was discovered possessing two 

 well formed and vigorous embryos as can readily be seen from the speci- 

 men submitted. The embryos are so far advanced that it is impos- 

 sible to determine their origin except that it is certain that they lay 

 within the same nucellus. Careful search in the field failed to reveal 

 any additional cases. 



