XXIX 



ARTIFICIAL PARTHENOGENESIS IN PLANTS 



Experiments on artificial parthenogenesis in plants arc 

 limited by the fact that it is necessary for this purpose to obtain 

 the unfertilized eggs in large numbers and that the eggs are not 

 naturally parthenogenetic. The Fucaceae seem to meet this 

 requirement and J. B. Overton, of the University of Wisconsin, 

 has recently succeeded in bringing about artificial partheno- 

 genesis in a species of Fucus at Woods Hole. Since only a pre- 

 liminary report has thus far appeared 1 on this subject it may be 

 best to quote from it. 



Fucus vesiculosus, a dioecious species, occurs near the shores 

 between tide marks at Woods Hole, and plants, both in the vegeta- 

 tive and reproductive conditions, are usually abundant. The sperma- 

 tozoids and oospheres are usually discharged sparingly during ebb 

 tide and abundantly during flood tide. Plants were collected during 

 ebb tide, the distal portions removed and placed in dishes on ice over 

 night. Care was taken that the conceptacles bearing eggs and sperms 

 were kept separate. When it was desired to obtain the eggs and 

 sperms, dishes containing conceptacles were filled with fresh sea-water, 

 or after first exposing the conceptacles to a hypotonic sea-water, when 

 eggs and sperms were discharged in large numbers. The freshly ex- 

 truded eggs drop to the bottom of the dishes and can be taken up with 

 a pipette and transferred to watch glasses for experiment. After a 

 short time the eggs show a tendency to adhere very firmly to the 

 bottom of the watch glasses so that fluids can easily be poured off 

 and others added without losing the eggs. 



In plants used to induce cell division by artificial means great 

 care was taken to prevent contamination by sperm. The female 

 plants were carefully washed with fresh water to kill any sperms which 

 might adhere to them. None of the eggs obtained from such sterilized 

 plants ever developed in the numerous controls, which were run in 



ij. B. Overton, "Artificial Parthenogenesis in Fucus," Science, XXXVII, 

 841, 1913. 



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