— ]6G — 



cells". „The behaviour of this cell recalls the tree cell formation, 

 which occurs in the early history of the macrospore". According 

 to the author's opinion an antipodal cell in fig. 3 shows an egg 

 cell. „It might be suggested that we have here a macrospore, in 

 an unusual position, but a macrospore, nevertheless". „In any 

 case, its origin is not that of the macrospore, but that of the 

 antipodal cell". 



I have not yet myself been able to examine this species but 

 it strikes me as possible that we here have something like the 

 apospory in Hieracium. Certainly the author points oat that the 

 origin of this cell cannot be a macrospore cell, but an antipodal, 

 on the other hand, however, a minute description of the embryo 

 sac development is not given, and besides a vegetative cell near the 

 embryo sac, which grows out in this manner, can very easily be 

 misunderstood as regards its origin. I may say that at first I also 

 had the opinion that the aposporic ES in Hieracium really was an 

 antipodal cell, until a careful study of its development taught me 

 its true origin. It is also worthy of attention that such antipodal 

 development in Aster, according to Chamberlain, is not always 

 to be found in this species. 



Opperman (14) has since examined the same plant and found 

 rather a peculiar case where a nucleus from the antipodal region 

 became an egg cell. The author, however, cannot fully explain 

 the real significance of this case. 



Apogamy is not described in Aster, but it will perhaps be 

 found there, as this genus is very polymorphous in America 1 ). 



In the hitherto described apogamic forms apospory is not yet 

 found, but perhaps some cases in Alchem.il la tend that way. 



Murbeck (11, 12) in his great and important work on Alche- 

 milla has, regarding some anomalies in this genus (12), described 

 a case of polyembryony which, however, he considers to be a 

 „Nucellarsprossung". In fig. 2 of his work (12) he depicts a large 

 cell in the nucellus: „Durch ihre Dimensionen iibertrifft diese Zelle 

 die Oosphare, allein die Ahnlichkeit mit einer solchen ist im iibrigen 

 auffallend". According to Murbeck's opinion this cell should 

 ,.sich zweifelsohne nicht als eine Macrospore verhalten haben, son- 

 dern sie hatte — durch Teilungen direkt einen Embryo hervorge- 



! Ostenfeld (16, p. 235) mentions briefly in a foot-note that he has made 

 castration experiments with several species of Aster, hut with negative 

 result. 



