316 THE ZOOLOGIST. 



yield an acid in the course of development, and perhaps their 

 growth might be unfavourably affected by substances derived 

 from the vessel which might be dissolved. A preliminary experi- 

 ment, however, in a small tin vessel showed that the development 

 of the bacillus proceeded without interruption. After this, four 

 large milk-can-like vessels, each containing sixty litres, were pre- 

 pared. These were filled with the straw-infusion, to which peptone 

 and grape-sugar had been added, neutralised with sodium carbonate 

 (mit kohlen-saurem Natron), and sterilised by being boiled thrice 

 for two hours in a current of steam. After the vessels had cooled 

 down to 40° C, they were charged with a pure culture of bacillus, 

 and submitted to a temperature of over 30° C. After two days, the 

 bacilli were developed in the vessels in great abundance. At the 

 same time, with the friendly aid of M. Pampoukis and his assistant, 

 M. Metaxas, 412 tubes were filled with pure culture on obliquely- 

 stiffened "Agar." With each Agar-tube we were able to impreg- 

 nate at least a litre of water in which the pieces of bread designed 

 to infect the voles were to be dipped. We had thus sufficient 

 material to infect a large district in case the bacillus-laden 

 infusion should have been spoiled in transport. 



On April 16th we set sail in company with M. Pampoukis for 

 Volos, arriving there early on the 18th, and took the train to 

 Larissa, the capital of Thessaly, in the neighbourhood of which 

 we were to commence our proceedings. On the road we en- 

 countered in the neighbourhood of Velestino great flocks of 

 Buzzards, Kites, Sparrowhawks, and Storks, flying around the 

 fields and fallow lands. It has been observed in other countries, 

 too, that an increase of Field Voles is usually accompanied by a 

 great increase of the various animals which prey upon them. The 

 railway traverses a wide plain, bordered on the east by the 

 Kissavos (the ancient Ossa), and on the north by the snow-covered 

 Olympus. The plain is bounded on the west by a low chain of 

 hills, and is the most important of the plains infested by the voles 

 near Larissa. The whole of Thessaly is really one vast plain 

 bordered by mountains, and divided by the range of hills just 

 mentioned into the plain of Larissa and the plain of Trikala. It 

 is traversed from west to east by the River Peneios, which 

 descends from Pindos into the plain near Kalabaka, south of the 

 wonderful rock -monasteries of Meteora, and leaves the plain 

 north-east of Larissa, between Olympus and Kissavos, forming 



