52 University, of California Publications in Zoology [VOL. 13 



TECHNIQUE 



New facts are usually brought to light by the discovery of new or 

 better methods. These afford a solid foundation for progress. Much 

 can be judged of the scientific value of results by a knowledge of the 

 methods used to obtain them. For this reason the methods employed 

 in procuring, preparing, and studying these animals are given in some 

 detail. 



Living Material. The material was obtained at the Oakland Meat 

 and Packing Company's stockyards, which are a forty-five minute 

 car-ride distant from the laboratory. The first problem was neces- 

 sarily to devise a means of carrying the stomach fluid which contained 

 these parasites from the slaughter-house to the laboratory without 

 allowing a fall in temperature, for as is well known, a loss of three 

 or four degrees Centigrade will cause the death of these animals. In 

 this connection it is interesting to note that of all the twenty-odd 

 species of ciliates described from the stomachs of ruminants the Diplo- 

 dinium ecaudatum series is the most sensitive to changes of tempera- 

 ture, a fact not heretofore recorded. 



Two points are kept in mind : the rapidity of obtaining the 

 material after the animal has been killed, and prevention of loss of 

 heat from the container while on the way to the laboratory. We go 

 directly to the killing floor and as soon as the viscera are removed 

 from an animal, which is usually within three to five minutes after 

 its death, an assistant removes the reticulum or ' ' honeycomb, ' ' turns it 

 inside out to remove the partly digested food material and then 

 wrings it as one would wring a wet cloth, into the operator's hand, 

 which is held cupped to receive the fluid. At the inner edge of the 

 hand, pressed close to the flesh, is the opening of the container, held 

 in such a manner that the hand forms a warm funnel which Collects 

 and transfers the fluid to the container with the least possible loss 

 of heat. By using a "Thermos" vacuum bottle contained in a well 

 insulated warm box it is possible to convey the stomach fluid from 

 the animal to the warm oven in the laboratory with a fall in tempera- 

 ture of not more than one-half of a degree Centigrade. Schuberg 

 (1888) after obtaining his material wrapped the glass container in 

 a cloth and carried it thus in his pocket for half an hour before 

 reaching the laboratory. Eberlein (1895) collected the stomach fluid 

 in test-tubes, which he placed, without wrapping, in his trouser's 

 pocket, where he carried them for an hour before reaching the labora- 

 tory. Eberlein notes that the temperature may fall as low as 20 C 



