ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



425 



down upon the plasticine in the groove, and plasticine pushed up 

 round its edge so as to ensure sealing. The dish is then tilted so that 



Fig. 62. — Sketch of one-half of the porcelain chamber. 

 A, B, Opposite portions of porcelain chamber, sepa- 

 rated by the partition K. C, Central aperture in cover- 

 ing of the porcelain chamber. D, Groove for reception of 

 plasticine. 



the pyrogailic and soda overflow the separating partition and mix. 

 Condensation water is retained in the upturned edge of the Petri dish 

 (figs. 61 and 62). 



The extent to which oxygen has been absorbed may conveniently be 

 shown by making a blue pencil mark on the upper surface of the 

 porcelain. When the oxygen is rapidly absorbed, this becomes bleached 

 within 48 hours. 



Partition of Plate Cultures.* — A Hahn describes a piece of appa- 

 ratus (fig. 63) for use in the preparation of plate cultures. It consists 



Fig. 63. 



of a star-shaped piece of glass fitting the Petri dish, consisting of six 

 rays, which divide the culture medium into as many compartments. It 

 is placed in position before the medium has solidified. The author con- 

 siders the ordinary method of plating cumbrous and wasteful, and points 

 out that this device, which enal)les six platings to be carried out on a 

 single dish, will involve considerable saving of time, labour, and space, 

 and facilitate the comprehensive survey of the results in any extensive 

 plating investigation. 



New Medium for Gonococcus.t — P. E. Weil and Noire recommend 

 the following medium as being very successful and satisfactory. The 



* Centralbl. Bakt., Ite Abt. Orig., Ixix. (1913) p. 228 (1 fig.), 

 t C.R. Soc. Biol. Paris, Ixxiv. (1913) pp. 1321-2. 



