STRUCTURE AND HISTORY OF PLAV. 235 
main theme of his book is the economie development of the flood-plain and 
delta of the Danube in Rumania. His chief observations on Plav, and 
deductions therefrom, I quote on pp. 241-246. 
My acquaintance with Plav dates from September 1912, when I went to 
Rumania to study the aquatic vegetation of the Danube valley and delta. I 
had for some years past been working at the vegetation of the Norfolk 
Broads *, and it was with the object of gaining, for comparative purposes, 
some knowledge of similar localities and their vegetation that I decided to 
visit the Danube in Rumania, where it seemed to me probable that the most 
primitive aquatic vegetation in Europe would be found. From September 
20th to October 22nd, therefore, I travelled through a great portion of the 
Rumanian Balta + (the inundation district of the Danube in Rumania), both 
in the region of the high floods and in the delta, the region of the low 
floods. In the former region my centres were Gostinu [Gostin], near 
Giurgiu, Cernavoda, the Balta of Braila and Tulcea. I crossed the delta 
almost entirely by water, from north to south, and also walked and drove 
with ox and horse along most of the shore of the Black Sea from Portita 
[Portitsa] near Lake Razim (see map), the southernmost part of the delta, 
to the Chilia mouth of the Danube f, the northernmost part of the delta in 
Rumania. In this way I got a general idea of the vegetation of the river 
valley and delta, and also saw Plav. With the express purpose of making a 
‘special study of Plav, I returned to the delta on September 3rd, 1913, and 
settled at the little Kirhana (fish-salting station) of Rosulet [Roshulets ], 
where I remained until October 11th. The results of my investigations on 
Plav are published here. 
The research was carried on with simple implements, chiefly with the 
rizak, a two-edged knife with a wooden handle about 2:5 m. (about 8 feet 
3 inches) long, used by the local fishermen for cutting Plav (see P1. 18. fig. 2 
-& РІ. 20); some pointed bamboos about 3:5 m. (about 11 feet 6 inches) т 
length for sounding purposes; a few wooden folding-rules 2 m. (6 feet 
6} inches) long for measuring out quadrats $; a pair of small milli- 
metre callipers for measuring the thickness of reed-rhizomes еѓс.; and a 
spring-balance weighing up to 56 Ibs.| (25'4 kilogr.) and graduated to 41b. 
(0:226 kilogr.), for weighing sheaves of cut reed. 
* See chapter X. of “ Types of British Vegetation," edited by A. G. Tansley. Cambridge, 
1911. 
T From Sept. 9th to Sept. 20th, I took short excursions in the Rumanian Carpathians, 
the plain region north of Bucharest and the steppe near Faurei. 
{ In 1913 I crossed the Chilia chatal (fork) of the Danube at Periprava and spent three 
days on the Russian side of the river at Vâlcov. I thus also saw something of the Russian 
portion of the delta. 
$ See Clements, E. F., * Research Methods in Ecology." Lincoln, Nebraska, 1906. 
|| It is my practice to give the measure which was actually used first, and its equivalent 
after it in brackets. 
R2 
