238 A IgcB and their Study. [Sess. 



Most Algae are true cosmopolitans, and this fact enables 

 us to use floras of other countries for the identification of 

 British plants. Even the tropics have not produced anything 

 strikingly new in this line, although we must confess that 

 comparatively little has been done so far in the study of 

 tropical fresh-water Algae. One other subject I must mention 

 here, as being of special interest to members of the Micro- 

 scopical Section of our Society, namely, the study of the 

 " plankton " or " floating organisms," as far as it relates to 

 the Algae, which constitute the greater part of the phyto- 

 plankton or plant-plankton. A great number of fresh-water 

 Algae are found floating in the water of our ponds and lochs, 

 and their study, as well as that of plankton as a whole, is of 

 fairly recent date, and will, as I understand, occupy the next 

 session of the Microscopical Section of our Society. 



I should like to say a few words in conclusion on the 

 collection of fresh -water Algae of Mid-Lothian for which 

 you have awarded me your prize. The 72 slides which I 

 have been able to send in represent only a small section of 

 the numerous species which might be found in Mid-Lothian. 

 I have already given you some of the reasons for the incom- 

 pleteness of the said collection. To make anything like a 

 thorough survey of the fresh- water Algae in such a district 

 as ours would mean several years' work to an amateur whose 

 time is limited. As the 41 species of my collection are only 

 a small fraction of those that can be found in our county, 

 I hope to be able in the future to increase considerably the 

 list of species actually collected in and around Edinburgh. 

 As far as I am aware, the only time that the fresh-water 

 Algae of our district received any attention was about eighty 

 years ago, by Dr Greville. The West Coast has been more 

 fortunate in that respect, as in the ' Flora of the Clyde Area/ 

 published by the Local Committee for the Meeting of the 

 British Association in G-lasgow in 1901, the fresh -water 

 Algae have received due attention, and the long list of species 

 found in that area testifies to the zeal and the skill of the 

 collectors who have contributed to it. A complete list of 

 the 41 species of my collection, as verified, and in many 

 instances corrected, by our principal authority on this subject, 



