Jan. 1891.] BOTANICAL SOCIETY OF EDINBURGH. 45 



ately the daily temperatures of the place in which the 

 cultivation is made. If this be consistently adopted, the 

 result will be that a greater possibility of constant growth- 

 characteristics will accrue, and the identification of species 

 in the light of previous descriptions will be more readily 

 accomplished. 



In conclusion, the use of this organism {B. arhorescens) 

 might be suggested in all bacteriological laboratories as a 

 test for the gelatigenous power of the media in use. The 

 practical utility of this suggestion is the more manifest when 

 we consider that dependent upon the amount of boiling to 

 which the gelatine is subjected, the gelatigenous power will 

 vary, and as it is quite impossible at present to give any 

 standard for the amount of boiling which should be adopted, 

 it is necessary to be able conveniently to discover the gelati- 

 genous power in the medium when it has been prepared 

 for use. 



On the Stkucture of Tmesipteris Forsteri, Endl. 

 By J. Melvin Lowson, M.A., B.Sc. 



The author described at length the structure of this plant 

 in the mature state, which is now growing in the Eoyal 

 Botanic Garden, pointing out dififerences between his interpre- 

 tation of the facts and the statements made by Bertrand, 

 based upon the examination of dried material. 



Dr Wilson, commenting on a remark that the gameto- 

 phyte of Tmesipteris was as yet unknown and that the allied 

 Psilotum was permanently apogamous, stated that in course 

 of the preceding year he learned from Dr Macleod of Ghent 

 that the germination of the spores of Fsilotum had been 

 recorded there, but that, unfortunately, the phases of ger- 

 mination and development of the sexual generation had not 

 been described by the observer who noticed the fact. 



