— 109 — 



rrassit. cell. veget, 10-12-15 p, altit. lj-2 plo major 

 oogon. 24-35 fx, •• 27-33 u. 

 oospor. 27-30 p., •• 24-30 p.. 

 stip. nannandr. llu, » 26-30 pu 

 cell. antherid. 7-9 p, » 7-9 f*. 



H. — Summary. 



We may briefly summarise the results of Uns investigation 

 as follows : 



I. — The algal flora of Barton's pond is dominated bv a suc- 

 cessive association (formation ?)of Microspora,Eunotia Arcus, 

 Conferva, Zygnemaceae, Oedogonium, Protococcales, Eugle- 

 'Ut, Anabaena, speciesof Trachelomonas, and epiphytic Dia- 

 toms. The flora is very rich and shows a very pronounced 

 periodicity, related somewhat to thaï of the Plianerogamic flora. 



II. — Font' main phases are distinguishable in the annual 

 cycle, viz. : 



(a) Winter-phase with an abundance of Microspora and 

 Diatoms. 



(b) Spring-phase with dominant Zygnemaceae and Oedogo- 

 nium, and numerous Protococcales as subsidiary i'orms. 



(c) Summer-phase with dominant Euglena and Anabaena, 

 lneffigiata and Desmids being important subsidiary forms. 



(d) Autumn-phase, chiefly characterized by renewed develop- 

 ment of many of the filamentons forms and bv the présence of 

 species of Trachelomonas and Oscillarieae. 



III. — The flora differs fundamentally from tliat of Abbot's 

 pool in the absence of Cladophora and Melosira, and in the 

 abundant development of Confervales. Thèse différences are 

 probably characteristic of two distinct algal associations (or 

 formations?). 



IV. — The gênerai trend of periodicity is the same in Bar- 

 ton's pond and Abbot's pool, there being in both cases a winter- 

 phase characterised by a hardy filamentous form and Diatoms, 

 a spring-phase in which Zygnemaceae play an important part 

 and amixed autumn-phase with Oscillarieae. The principal dif- 

 férence lies in the summer-phase and is due to the normal drying 

 up of Barton's pond during that period. 



V. — A profound relation between the frequency of the algal 

 flora and the meteorological conditions lias been etablished. 



