FERTILIZATION BY AUTOGAMY 



141 



nuclei, but of masses of idiochromidia which in other protozoa become 

 differentiated into such nuclei. The karyosome and some of the 

 peripheral chromatin form a degenerating "somatic" nucleus which 

 takes no part in the later processes. 



The further fate of the encysted form thus brought about has not 

 been followed, but in Entameba histolytica, according to the observa- 

 tions of Schaudinn and, later, of Craig ('08), such a stage is followed 

 by spore formation. Schaudinn ('03) observed, and his observations 

 have been confirmed in every detail by Craig ('OS) upon living and 

 fixed material, that in this ameba the nucleus fragments into idio- 



FiG. 58 







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k;.i>7 \,-' -.,r :.'<-.. ^- ::.■■'■ ;.y^:i:^ 



fm 



Entameba histolytica. (After Craig.) A, organism showing rods and granules of chro- 

 matin in tlie nucleus, vacuole with some stained substance, and dense ectoplasm; B. the 

 chromatin of the nucleus passing into the cell plasm, where it is distributed as chromidia, shown 

 in C; D, aggregation of chromidia to form secondary nuclei (see Fig. 51, of Ameba limax); E, 

 "spore formation" by budding; F, spores of Entameba histolytica as seen in feces. 



chromidia (chromidiaj which collect in masses at the periphery, and 

 these masses, with some cytoplasm, are protruded from the surface as 

 buds. The buds become covered with a hard and resistant membrane 

 which is so deeply colored l)y the intestinal fluids that further internal 

 processes could not be followed (Fig. .")S\ Neither Schaudinn nor 

 C'raig observed union of these idiochromidia masses, and the resem- 

 blance to Ameba Umax can only be inferred from the similarity of 

 preliminary processes. 



In the closely allied forms, Entameba coll, Entameba mnris, and 

 Ameba proteus, the process of autogamy is somewhat more compli- 



