1895. RESULTS OF ''CHALLENGER" EXPEDITION. 25 



Fig. 2. — Pyrocystis noctiluca, Murray ; 

 100 times nat. size. 



Moseley's otlier duties on board and other interests, it is a remarkable 

 collection — as good a collection as would have been made by most 

 young botanists with nothing else to do. The other sources of the 

 Algee collected were not of so much geographical interest ; but in all 

 cases the results have been welcome. 



The main interest, however, of the expedition to botanists is in 

 the Hght shed on the Algae of blue water — the plankton Algae of the 

 open sea, removed from the influence of coast and river waters. 



This expedition first taught us the 

 great extent of this flora, though 

 observations, such as those of Sir 

 Joseph Hooker in the Southern 

 Ocean, of Dr. Wallich, and 

 others, had led botanists to expect 

 the existence of a universal pe- 

 lagic flora. Dr. John Murray's 

 observations, published in the 

 Narrative and in the Smmnary, are 

 by far the most important contri- 

 bution to our knowledge of the 

 distribution of these forms ; and 

 the recent Hensen Expedition 

 has added but little to it. How-, 

 ever, all that has yet been done in the study of this flora is to 

 advertise its existence, and to proclaim to botanists the urgent need for 

 its exploration. The marine Peridinieae, Pyrocystis (Fig. 2), the Cocco- 

 spheres (Fig. 3) and Rhabdospheres, and other forms like Halosphcrra — 



noted but not yet 



described — all need 

 working out. The Cy- 

 anophyceae and Diatoms 

 are, perhaps, of less 

 biological interest at 

 present ; but much has 

 yet to be done with 

 them too. Castracane's 

 report on the Diato- 

 maceae {Botany, vol. ii.) 

 has added a great 

 number of new species 

 to the overwhelming 

 number already existing 

 —and it has been criti- 

 cised with some severity 



1 i. -u ^ -1. , Fig. 3 — A Coccosphere ; i.ooo times nat. size, 



by experts — but it, to- i- ■ • 



gether with Mr. Comber's hard work contributed to the Summary, forms 



a notable addition to ourknowledge of these forms and their distribution. 



