558 THE AMERICAN NATURALIST. [VoL. XXXIX. 



tops of young flowers that several species of Taraxacum pro- 

 duced normal seeds apogamously and concluded that the embryo 

 must develop parthenogenetically since Schwere, in 1896, traced 

 its origin from the egg. Ostenfeld (: 043., : 040) from failure to 

 find pollen on the stigma of Hieracium and failure to make it 

 germinate in a number of solutions, was led to try similar experi- 

 ments to those of Raunkiaer in cutting off the anthers and stig- 

 mas of flowers. He found that a large number of species of 

 Hieracium were able to set seed apogamously and he believed 

 parthenogenetically but histological investigations were not made 

 to establish the last point. The experiments of Raunkiaer and 

 Ostenfeld are interesting as showing how a form by virtue of its 

 parthenogenetic habits might become segregated and quite re- 

 moved from the probability of hybridization. Murbeck (: 04) in 

 a short paper announced that the embryos in Taraxacum ancj 

 Hieracium, developing from flowers whose stamens were cut out 

 (as in the experiments of Raunkiaer and Ostenfeld) actually do 

 develop from the egg cell and are therefore parthenogenetic. 

 Murbeck also failed to find pollen tubes in the ovules where 

 pollen had been applied to the stigma. Winkler (: 04) reports 

 that Wikstrcemia indica matures very little perfect pollen and 

 produces its seeds apogamously, as proved by experiment. The 

 embryos are stated to develop parthenogenetically from the egg 

 but no details are given in this preliminary paper of the chromo- 

 some history. This group of contributions while very interest- 

 ing, presents no data on the fundamental problems in a cyto- 

 logical explanation of parthenogenesis. 



Murbeck (:oia) concluded for Alchemilla that true tetrads 

 were formed previous to the differentiation of the embryo-sac 

 but nevertheless found evidence that there were no reduction 

 phenomena so that the nuclei within the embryo-sac contain the 

 sporophytic number of chromosomes. Mur beck's evidence of 

 tetrad formation was not satisfactory and in the light of recent 

 studies of Strasburger (: O4c) cannot be accepted. His view 

 was, however, correct that there is no reduction of the chromo- 

 somes in the formation of such embryo-sacs as produced par- 

 thenogenetic embryos. 



Juel (: oo) gives a critical comparison of the development of 



