NOTES ON TRICHINAE. 



S. CALVIN. 



Some years ago a series of observations was conducted in 

 the Biological Laboratory for the purpose of ascertaining 

 facts concerning the prevalence of trichinae among Iowa swine. 

 The work in the laboratory was supplemented by observa- 

 tions made by students and others at a number of different 

 localities throughout the state. Specimens of muscle taken 

 from some hundreds of individuals were examined, but press 

 of other duties interrupted the work before it was regarded as 

 finished. Without entering into details the results as far as 

 ascertained may be briefly stated as follows: — 



I. Hogs kept for some time at our local slaughter yards 

 and allowed to feed on offal show a high percentage of 

 animals affected with trichina. Observations made in differ- 

 ent parts of the state agreed closely and showed that among 

 hogs so fed one in every ten or twelve contained these muscle 

 parasites. Only a small proportion of those having the para- 

 sites, however, contained them in sufficient numbers to be 

 dangerous to persons eating the uncooked flesh. 



II. Hogs kept in towns by private families and fed in 

 small close pens also show a high percentage of trichinous 

 individuals. 



III. Hoors coming from the farms, fed on corn and fatten- 

 ed in large numbers in open fields, are almost entirely free 

 from trichinae. These are the animals that supply the great 

 packing houses, and the fact is that an examination of more 

 than three hundred specimens from as many different individ- 



