M 77/, Trichina Spiralis. 



A digestive canal runs the whole length of the animal, 

 and at its posterior part is a closed aac running about oue- 

 third of its whole length and filled with granular matter. 

 No sexual organs are to be seen. 



If portions of this muscle are introduced into the stomach 

 of certain animals (as rabbits For example), and these ani- 

 mals are killed and examined at difFerenl intervals, we find 

 that the Trichina passes through the following stages of 

 development. 



During the three days following its ingestion it grows 

 rapidly iu size, becoming from three to four times its ori- 

 ginal length. At the same time sexual organs are deve- 

 loped, and the closed sac, mentioned above as occupying the 

 posterior portion of the body, becomes ovaries in the female 

 and testicles in the male, and within from eight to ten 

 days from the time of their entrance into the stomach each 

 female Trichina gives birth to living young whose number 

 has been estimated at from two hundred to one thousand 

 from each parent. Whether the same individual becomes 

 pregnant more than once, is not yet fully determined, but 

 from some of the facts observed it is probable that they do. 

 The young Trichina- are exceedingly minute and thread- 

 like, and commence immediately afterbirth to bore through 

 the walls of the stomach and intestines containing them, 

 and disseminate themselves with wonderful rapidity all 

 through the muscular tissue. It is a curious fact that they 

 are found to locate themselves only in the tissue of those 

 muscles which are under the control of the will, never 

 having been found in heart or muscles of organic life. 

 After reaching their destination in the muscle they in- 

 crease gradually in size until they attain one-twenty-iifth 

 of an inch in length, and then coil up in a spiral form and 

 remain quiel in the midst of the deposit of fibrinous matter, 

 which the irritation of their presence has caused to be depo- 

 sited around them by the vessels supplying nutriment to the 



