272 BACTERIA IN OTHER FOODS 



rolled meat may be a source of infection to a greater degree than 

 the ordinary fresh joint, and this is borne out by the experience 

 derived from epidemics due to meat-poisoning. 



Tuberculous meat also finds its way occasionally into sausages, 

 and other similarly prepared meat foods. 



Swine Fever is not an uncommon disease of pigs, and makes the 

 meat unfit for food. Schiitz and others have isolated a bacillus from 

 this disease. The chief post-mortem signs are the red punctiform 

 rash, generally becoming confluent on the back, extremities, and 

 ears ; the ulceration of the intestine, and the characteristic mottling 

 of the lymph glands. 



Anthrax (see p. 315), Actinomycosis (see p. 321), and other condi- 

 tions are described elsewhere. Many parasitic diseases also make meat 

 imfit for food. 



3. Ice-cream 



In 1894 Dr Klein had occasion bacteriologioally to examine ice- 

 cream sold in the streets of London. In all six samples were 

 analysed, and in each sample the conclusions resulting were of a 

 nature sufficiently serious to support the view that the bacterial 

 flora was not inferior to ordinary sewage. The water in which the 

 ice-cream glasses were washed was also examined, and found to 

 contain large numbers of bacteria. 



Since that date many investigations have been made into ice- 

 cream. It appears that this luxury is frequently manufactured 

 under extremely objectionable circumstances, and with anything but 

 sterilised appliances. Little wonder, then, that the numbers of 

 bacteria present run into millions per c.c. (varying from two to 

 twenty millions or more). In nearly all recorded cases, the quality 

 of the germs as well as the quantity has been of a nature to 

 cause some concern. B. coli communis has been very commonly 

 found, and in considerable abundance. The Proteus family, which 

 also possesses a putrefactive function, is common in ice-creams. 

 The common water bacteria are nearly always present. B. typhosus 

 itself, it is said, has been isolated from some ice-cream which 

 was held responsible for an outbreak of enteric fever. The 

 material had become infected during process of manufacture in the 

 house of a person suffering from unnotified typhoid fever. 



The Marmfacture of Ice-cream. — There are, practically speaking, three methods 

 of manufacture: — 



(1) The real ice-cream, which cannot be sold at a low price, and which is made 

 simply by mixing cream (with a small proportion of milk), fruit or fruit pulp and 

 sugar. This mixture is then at once frozen. 



(2) Milk is flavoured with fruit, or fruit essence and sugar, and has then added 

 to it a small quantity of dissolved gelatine, and at once frozen. In these two 

 processes there is no boiling, and both are frozen immediately after mixture. 



