BACTERIOLOGICAL EXAMINATION 



147 



Castor beans are not infrequently used as adulterants of oil meals, peanut meal, 

 etc., especially those of South Russian origin. The presence of ricin (a toxin) 

 gives them their poisonous character (gastroenteritis, nephritis, agalactia, fainting, 

 spasms, death). 



Microscopically their thick, slivery, sharp-edged and longitudinally marbled skins 

 are characteristic. Macerated material shows the radially arranged palisade cells 

 (Fig. 82) and the parenchyma with its varied spiral tubes (Fig. 83). 



The decorticated seeds have little that is characteristic to distinguish them 

 microscopically. Their presence is determined by the complement fixation test 

 (p. 134). 



4. Bacteriological Examination 



The spoiling or decomposition of air-dry feeding stuffs (meals, brans, oil cakes, 

 etc.) is caused chiefly by molds. 



Fig. 83. Castor bean seed. 



Parenchyma of the seed after treatment 



with ether and alcohol. 



a, Spiral tube of tire seed coat. 



Fig. 84. Castor bean seed. Elongated cells of 

 seed coat after treatment with ether and caus- 

 tic potash. (X 300.) (After Koenig.) 



For the detection of their presence we resort to — 



1. Odor. Musty, moldy, sour or rancid odors indicate the presence of mold fungi. 



2. Cultural methods. For this purpose use covered Petri dishes containing a 

 layer of sterilized sand 2 to 5 mm. in thickness. Two grams of the feeding stuff 

 to be examined are spread over the sand with the aid of a sterilized brush and 

 moistened with water which has been slightly acidulated with lactic acid. Some of 

 these dishes are kept at a temperature of 37° C. (98.6° F.). and others at ordinary 

 room temperature. Good feeding stuffs will show at most an insignificant moldiness 

 after 24 hours and do not smell putrid, musty nor rancid. 



For the detection of mites see Klimmer, Hygiene. 



