476 



Journal of Agricultural Research 



Vol. XV, No. 8 



i^^^Ci/4^ci 



that watch glasses which but two hours earlier contained numerous 

 larvge had become almost free from the worms. This phenomenon was 

 so striking that it was studied in detail as to the method of occurrence. 

 The worms utilized in these observations were obtained from the host 

 24 hours after artificial infection. For the first 2 or 3 hours after the 

 larvae were isolated and kept at room temperature, the phenomenon 

 was but seldom observed. Later, epidemics of disintegrations were noted, 

 and worms at various stages of degeneration were readily found. The 

 first sign of the process is a granulation of the worm at one end, more 

 often at the anterior end. This is followed by a disappearance of the 

 granules, the worm becoming gradually smaller. Occasionally the 

 writer noted parasites in which the tv/o ends had degenerated and the 



middle part was still intact. The 

 wave of disintegration spreads slowly, 

 and involves not only the internal or- 

 gans, but the cuticle as well. In this 

 respect, as will be shown later, the 

 process differs from disintegration 

 induced by potassium cyanid. 



The writer was at first inclined to 

 believe that the absence of the in- 

 testinal contents of the host was per- 

 haps responsible for the degenerative 

 changes of the worms. However, 

 even when the worms were kept in 

 salt solution to which the intestinal 

 contents of the host were added the 

 process still occurred. 



Several interesting speculations 

 suggest themselves in this connection. 

 The degeneration may perhaps be associated with a failure to undergo 

 successful molting. It is not at all imiprobable that worms which have 

 been stimulated by certain factors of the intestinal environment should, 

 after sudden removal from that environment, undergo degenerative 

 changes. There is a further possibility that the lack of proper food may 

 check the impulse to growth and development, and lead to the process 

 of degeneration. Finally, it is possible that concomitant with the 

 growth of these parasites they liberate toxic substances which in an 

 artificial environment exert a deleterious effect upon the parasites them- 

 selves. The last hypothesis can be subjected to experimental verifica- 

 tion and the writer hopes to study this phase of the subject in connection 

 with studies which are now in progress on the possible presence of toxic 

 substances in the sera of hosts harboring trichinae. It may be mentioned 

 that Tallqvist (7) found in Bothriocephalus laius a proteolytic ferment 

 which was capable of destroying the proglottids of that tapeworm. 



fo) 



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i/io mm: 



Fig. I. — Skeleton outlines of two dwarfed trichi- 

 nae after the first molt outside of the host and 

 of two unmolted larvae from the same host 

 about 18 hours after artificial infection. 



