Morphologie, Teratologie, Befruchtung, Cytologie. 371 



tion of the embryo, rapidity of the seed matuiation, significance of 

 the reduced embryosac, chromosome behaviour as Ko the evolution 

 of parthenogenesis), unpollinated flowers under different conditions 

 (flower on the inflorescence axis bearing fertilized flowers, abscised 

 flower or tiower-bud, flower of the unpollinated stock, flöwer on 

 the abscised inflorescence axis), pollinated flowers under different 

 conditions (activity of old pollinium, period of pollination, pollina- 

 tion of young and of old flowers, pollination into the ovary, seif- 

 and cross-pollination , pollination of flowers on the abscised inflo- 

 rescence axis, pollination of abscised flowers, pollination of flowers 

 with broken ovaries), Stimulus upon the Stigma, pollination with 

 foreign poUen (the pollinium of Bletia hyacinthina, influence of the 

 Bletia-^o\\\Vi\\\vsx upon the act of fertilization of the Gastrodia-'^QWx- 

 nium, the pollens of other plants) and general considerations on the 

 results of experiments (action of the pollen or pollen-tube on the 

 ovular and ovarial development, correlation between the develop- 

 mental phases in the fruit formation, parthenocarpy, polyembryony, 

 the embryosac in the ovule developing into the embryoless seed. 

 parthenogenesis, development of the sporophytic tissue of the ovule). 



The Chief facts, resulting from his researches, are summarized 

 by the writer: 



The flower is, in a high degree, resistible towards various 

 kinds of treatment, and the embrj^onal development exhibits extreme 

 simplicity and is completed with great rapidity. On this account 

 GastYodia offers the best-suited material for the experimental study 

 on the embryonal development in Angiosperms. 



The embryosac is completed 3 — 4 days after bloom, and the 

 same interval of time is required for the pollinium applied to the 

 Stigma to produce the pollen-tube at füll development. So that in 

 the flower pollinated the day of bloom fertilization takes place after 

 3 — 4 days. The seed ripens after about 14 — 15 days, while the 

 dehiscence of the capsule occurs still later. 



The ovule is rudimental at the time of bloom, but, differing 

 from most orchids, the embryosac is completed without the Stimu- 

 lus of the pollen-tube. 



The embryosac is four-nucleate, being derived from one me- 

 gaspore. 



The heterotype mitosis does not follow precisely either the 

 parasynaptic or the telosynaptic type. The bivalent chromosome is 

 formed when the Univalent chromosomes come upon the equatorial 

 plate. 



A certain number of embryosacs is formed without the chro- 

 mosomereduction. 



The occurrence oi the diploid egg is most probable, but in no 

 case does parthenogenetic development take place. 



The sterility of a certain number of ovules may be explained 

 as being due to the Omission of the chromosome reduction in for- 

 ming the embryosac. 



Double fertilization takes place. The endosperm nucleus is the 

 product of the triple fusion of the male, synergid, and pole nuclei. 

 It remains undivided. Fertilization is effected with the pollinium 

 introduced into the ovarial cavity. 



Both, autonomic and aitionomic parthenocarpy may occur: The 

 size of the resulting fruit depends on the nutritive condition, but 

 under the same condition the aitionomic parthenocarpy gives rise 

 to a larger fruit than the autonomic. 



