SILICA JELLY 65 



with a sterile needle, and the material to be inoculated is 

 introduced into the egg by means of a glass capillary tube, 

 from which it is blown with great care. The hole is now 

 closed with sterile cotton-wool. This method of cultiva- 

 tion is particularly well adapted for the cultivation of the 

 anaerobic bacteria. 



(18) Bread. — Bread and pastes formed by boiling up 

 wheaten flour or ground rice with water are employed 

 particularly for the growth of moulds. Slices of bread or 

 layers of the paste are placed in Petri dishes and steamed, 

 as in the case of other media. 



(19) Malt Extract. — Solutions of malt extract and in- 

 fusions of raisins and other fruits are extensively employed 

 in the study of the yeasts. The foregoing materials 

 thickened with gelatine or agar are useful for the growth 

 of those organisms which, like the yeasts and moulds, are 

 favoured by an acid medium. 



(20) Irish Moss Jelly. — This medium was devised by Miquel 

 for the study of the ' thermophilic ' organisms, which do 

 not grow at a lower temperature than 50° C. This medium, 

 generally known as Miquel's high temperature jelly, is pre- 

 pared as follows : 400 grammes of Irish moss (Carragheen, 

 Fuscus crispus) are placed in 10 litres of boiling water and 

 boiled for several hours ; the liquid is then passed through 

 a sieve, the filtrate boiled again, and strained through fine 

 linen. The filtrate is slowly evaporated on a water-bath, 

 and the residue dried at about 45° C. On adding 1 to 2 

 per cent, of the gelatinous substance so obtained to ordinary 

 nutrient broth, a culture medium is obtained which remains 

 solid at 50° C. 



(21) Silica Jelly. — This novel and ingenious preparation, 

 which is wholly destitute of organic matter, was devised by 

 Klihne, and was used by him and Frankland in their re- 

 searches on the organisms of 'nitrification,' which will not 



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