Nov. 25. 1918 Observations and Experiments on Intestinal TrichincB 48 1 



(2) The passage of the larvae through the stomach does not stimulate 

 them to further growth and development, and a brief sojourn in the intes- 

 tine is insufficient to initiate those processes which lead to sexual maturity. 



(3) Larvae from the intestine that have not yet been stimulated to 

 further development become tightly coiled when removed from the host 

 and placed in a physiological salt solution, but those which have been 

 stimulated to development apparently lose the power of becoming 

 tightly coiled under similar conditions. 



(4) Larvae which have been stimulated to further development in the 

 intestine will molt even after being removed from that organ. The 

 molting process may be hastened by high temperatures and suppressed 

 by low temperatures. 



(5) Larvae which have not yet been stimulated to further development 

 in the small intestine can not be caused to molt by a high temperature. 



(6) With the beginning of development in the small intestine the larvae 

 lose the power of surviving for considerable lengths of time outside of the 

 host. They afterward become more persistent, however, in direct propor- 

 tion to their increasing age. 



(7) When removed from the host within 24 hours after artificial infec- 

 tion intestinal trichinae often undergo spontaneous disintegration which 

 may be due to the sudden change of environment, lack of food, or possibly 

 the liberation of toxic substances which affect the parasites while in an 

 artificial medium. 



(8) Larvae which molt after removal from the host have been observed 

 occasionally to decrease in size. It is suggested that the dwarfed condi- 

 tion is possibly due to lack of food. 



(9) After the first and subsequent molts the tolerance of the larvae to 

 various toxic agents is replaced by a marked sensitiveness to such agents 

 which decreases, however, with advancing age. 



(10) Under the influence of potassium cyanid the worms undergo dis- 

 integration and exhibit susceptibility to the poison along the major axis 

 which in the growing forms appears to be greatest in regions where growth 

 takes place most rapidly. 



(11) Modifications in the permeabiHty of the cuticle do not appear to 

 be directly responsible for the changes in susceptibility. The changes 

 probably result from a reorganization of the protoplasm coincident with 

 growth, differentiation, and age. 



(12) Attempts to induce molting in the larvae which have been decap- 

 suled by artificial digestion and afterwards kept in vitro under various 

 conditions have thus far failed to yield successful results. 



