444 ELMER L. SHAFFER. 



Goldschmidt ('09) and his students. As has been before men- 

 tioned, there have been many descriptions of cytoplasmic bodies 

 whose origin has been attributed to material extruded from the 

 nucleus. According to Goldschmidt and others (Buchner, Jor- 

 gensen, Schaxal, Wasilieff, Popoff, etc.), mitochondria are derived 

 from the chromidia and ultimately from the chromatin of the 

 nucleus, and are hence similar to Hertwig's "chromidia." The 

 fact that the mitochondria lie at the pole of the nucleus where the 

 idiozome lies and toward which the synaptic threads are polarized, 

 has been taken by Buchner and Wasilieff to be the place where 

 mitochondria arise by the emigration of chromatic materials 

 from the nucleus into the cytoplasm. Buchner ('09) derives 

 the mitochondria of the spermatocytes of Gryllus from the 

 material of the sex-chromosome, which in the bouquet stage 

 becomes vacuolated and shows evidences of disintegration. 

 While chromatin from the nucleus may at times come to lie in 

 the cytoplasm (e.g., chromatin diminution processes in Ascaris 

 and Miaslor, etc.), yet there is no strong evidence that it may 

 give rise to the mitochondria. It is difficult to see how escape of 

 chromatin from the nucleus could account for the tremendous 

 increase in the mitochondria as found during the growth period 

 of the oocytes of Cicada. Furthermore, the difference of behavior 

 of chromatin and mitochondria towards fixing fluids and specific 

 stains indicates that they are of a totally different chemical 

 nature (see Cowdry '16, p. 426). 



According to the view of Vejovsky ('07, '12) the mitochondria 

 are cytoplasmic structures having their origin in the "regressive 

 modification" (Duesberg, '12) of the sphere material. Mont- 

 gomery ('n) expresses the opinion that "it is probable that they 

 (mitochondria) are produced by either idiozome or nucleus or by 

 a joint action of both" (p. 787). Although it is quite usual that 

 the mitochondria are found lying close to the idiozome or sphere, 

 there is no conclusive evidence that they have their origin in 

 or from the sphere material. 



We have now discussed the three views prevalent regarding 

 the origin of the mitochondria. From a study of the mito- 

 chondria of Cicada and from a review of much of the literature 

 bearing on the subject, still another view presents itself which 



