DERIVED ORGANIZATION 87 



nuclei are not differentiated until the third division of the fertiliza- 

 tion nucleus (e. g., in Cryptochilum nigricans, Paramecium caudatum, 

 Par. putrinum, Bursaria truncatella, Carchesium polypinum, Oper- 

 cularia coarctata, Ophrydium versatile, Vorticella monilata, V. nebu- 

 Ufera, etc.); in other cases differentiation occurs after the second 

 divisions (e. g., in Anoplophrya branchiarum, Colpidium colpoda, 

 Di<l in in hi nasutum, Glaucoma scintillans, Leucophrys patula, Lio- 

 notus fasciola, Paramecium aurelia, Par. bursaria, Blepharisma undu- 

 lans, Spirostomum teres, Euplotes patella and charon, Onychodromus 

 grand is, Stylonychia pustulata, Uroleptus mobilis, etc.); and in still 

 other cases the differentiation takes place after the first division 

 (e. g., Chilodon uncinatus). In all cases both macronucleus and 

 micronucleus are formed by metamorphosis of such products of 

 division of the original nucleus after conjugation, the former by a 

 remarkable increase in size and in quantity of chromatin, the lat- 

 ter by reduction in size and concentration of the chromatin; the 

 former becomes a metabolic organoid of the cell, the latter a germinal 

 organoid. 



Mention may be made here of the vesicular nuclei which arise 

 by a process of so-called free-nuclei formation from chromidia, the 

 evidence for which is difficult to interpret otherwise. It rests, in the 

 main, on the observation of Hertwig as early as 1876, and again in 

 1899; of Schaudinn in 1903; of Lister, 1905; of Goldschmidt in 1907; 

 Elpatiewsky in 1907, and Swarczewski in 1908. In all cases the free 

 nuclei arise by the association of chromidia or chromidiosomes which 

 have been derived from the nucleus and distributed in the cyto- 

 plasm (see p. 69). Both Elpatiewsky and Swarczewski describe the 

 formation of the minute gametes of Arcella vulgaris by the fragmen- 

 tation of the cytoplasm into minute cells about these free nuclei. 

 These gametes move off as minute amebae leaving the parent with 

 its "primary" nuclei, which ultimately degenerate. Each of these 

 gametes contains at first a few scattered granules derived from the 

 chromidial mass which ultimately unite to form the gamete nucleus. 

 The process is more minutely described by Goldschmidt in connec- 

 tion with the mastigameba Mastigella vitrea. Here a chromidial 

 mass forms on the outside of the nuclear membrane by transfusion 

 of chromomeres (Fig. 45). After separation of this mass from the 

 nucleus, the chromatin granules come together in groups and form 

 nuclei about which minute gamete cells are cut out from the cyto- 

 plasm while the primary nucleus remains intact. The same thing 

 in principle is illustrated by the origin of the germ nucleus inside 

 the nucleus of Gregarina cuneata and other gregarincs as well (see 

 Fig. 55, p. 101). A somewhat similar mode of formation of the 

 microgamete nuclei of Coccidium schubergi was earlier described by 

 Schaudinn. This type of nucleus formation, according to Minchin, 

 represents the possible origin of Protozoa of "cellular grade" from 



