WORMS. 



211 



toil niul first named by Kichard Owen, wlio jiuhlislicd ;i very inaccurate description 

 of them in 1835, but tiie origin and dangerousiiess of these parasites was never siis- 

 jK'ctcd until 1860, when the investigations of Zenker, Leuckart, Pagenstecher, and 

 \'ircliow suddenly revealed the dan- 

 ger by ascertaining the history of the 

 trichina and its pathological action, 

 'i'lie whole civilized world was horri- 

 fied at the discovery of the great and 

 niithought-of risk which our daily 

 meals involve. Everywhere the in- 

 formation was spread, and never, per- 

 haps, has any subject occasioned such 

 iini\ersal discussion as this new know- 

 ledge. In the intestine the trichina 

 grows rapidly, the female becomes 

 about an eighth of an inch lo!ig, but 

 the male does not measure over a six- 

 teenth. The eggs in the female have 

 no shell, and develop to tiny embryos 

 within the body of the parent. The 

 ailult worm is thin and ta]iering to- 

 wards the head. A number of related 

 species and genera are known, but 

 none are so dangerous as the 7'ri- 

 cldiia spiralis, although one form, the 

 Trichocephalus dispar is not rare in 

 the human colon. 



Of the STR0N(;vi,in^ several 

 s[iecies attack man, for exam]ile 

 Kustronriyhis f/i(/as, Dochmiits du.o- 

 deiialis, etc., but the species we select 

 for a special biograjihy is the one so 

 detested l)y poultry raisers as the 

 cause of the "gapes." The ])arasitc in 

 ((uestion goes by the n.ame of Si/n- 

 (/iimiis tmcJiealis, and inh.abits the res- 

 jiiratory jiassages, tracheae and bronclii 

 of birds, living in bunches, which soon 

 enlarge so much that breathing be- 

 comes difficult to the unlucky bird, 

 which gasps for air, — the name 

 "ga])es" 7-efers to the characteristic 

 symptom of the disease. The generic 

 n:ime St/nr/aimis refers to the pecu- 

 liarity of the small males of attaching themselves to the large females to form indis- 

 soluble pairs. The constant effort to dislodge the parasites by coughing serves to 

 •'xjiel the eggs laid by the female; the eggs are thus scattered about, and are swal- 

 lowed again by other birds, .-ukI thus the disease is sjiread. In a hcnticiy the malady 



- Syngamus trachealii 



nale; b, female 



