LIN^EAN SOCIETY OF LONDON. 5 1 



Submitted to the same cultural conditions, A and B produced 

 a sward oF plants with large discoid male "flowers" oiihj, no 

 sporogonia being produced at auy time, C produced plants bearing 

 male and female organs resulting in a dense crop of sporogonia. 



It appears possible that vegetative development from structures 

 borne on male and female branches respectively may, if a sex- 

 segregation has .'ictually occurred somatically, lead to the production 

 of distinct male and female plants. If such is the case, the purity 

 of the gamete in mouoicous forms is secured by a somatic segrega- 

 tion in baploid tissue. 



Fi'om other evidence it seems clear that the point at which 

 segregation occurs is not necessarily fixed, but may be shifted 

 backward in the life cycle until, occurring with sporogeuesis, the 

 dioicous habit of the gametophyte is established. In this way 

 the dioicous condition might co-exist with the monoicous, or the 

 monoicous condition might be accompanied by distinct male plants. 

 Vegetative propagation from sex-segregated branches would also 

 lead to the various sex-forms of any one species. 



Mr. Bateson and Mr. H. N. Dixon contributed further remarks, 

 and the Author replied. 



Mr. A. O. Walker, F.L.S., explained the method he had adopted 

 at Ulcombe, Kent, amongst the school-children, with its success, 

 eight common species being taken for reports on their flowering 

 during three years, showing the remarkable difference between 

 the dates of 1916 and 1917, when, in the latter year, the cold 

 spring caused a delay of from four to six weeks in flowering. (See 

 Abstract, p. 60.) 



Mr. John Hopkinson, Dr. A. B. Eendle, and Dr. E. J. Sahsbury 

 spoke on the subject, Mr. Walker replying. 



ABSTRACTS. 



The Germination of Iris Psexulacorus, Linn., in Normal and 

 Abnormal Conditions. By Lt.-Col. J. H. Tull Walsh, 

 I.M.S., F.L.S. 



[Read 1st November, 1917.] 



Those who were present at the meeting held on the 30th of 

 November, 1916, will remember that Mr. T. A. Dymes, F.L.S., 

 told us rather a snd story about his experiences with the seeds of 

 the Yellow or Water-Flag. He told us that " those [seeds] that 

 fall on to the mud and remain there appear to perish from 

 decay." " Seeds that have not sunk germinate on or near the 

 surface of the water in the latter half of May." " The fate of 

 those seeds, if any, that sink before germination has not yet 

 been determined." I am not here to criticise Mr, Dymes. 

 Under the conditions in which the seeds he used were expected to 

 germinate, his results were correct. Seeds floated on deep water 



