PHENOMENA ACCOMPANYING FERTILIZATION 311 



Mulsow's contention is proved by finding final progamous spindles 

 in the anaphase stage with 4 chromosomes in each daughter plate 

 (haploid) while other progamous spindles are present in the same 

 section with S chromosomes in each daughter plate (diploid) (Calkins 

 and Bowling, 1926). Evidence in support of Dobell and Jameson's 

 generalization is furnished by the fact of the frequent occurrence of 

 an odd number of chromosomes in nuclei of different gregarines. 

 Thus 5 chromosomes were found by Shellack (1907) in Echinomera 

 hispida and the same odd number by Leger and Duboscq (1909) in 

 Nina gracilis; while 3 were found by Shellack in Monocystis ovata 

 (1912). Such odd numbers are not difficult to interpret if reduction 

 takes place at the first metagamic division but they lead to question- 

 able hypotheses of "odd chromosomes" (Leger) "accessory chro- 

 mosomes," etc., if reduction is interpreted as taking place prior to 

 fertilization. 



B. Disorganization and Reorganization. — (a) Phenomena of Dis- 

 organization.— While the meiotic processes are probably universal 

 accompaniments of fertilization they do not comprise all of the 

 phenomena taking place at this period. Evidences of disorganiza- 

 tion are apparent in the cell quite independent of the gametic 

 nuclei. Metagamic activities involving reorganization of the proto- 

 plasm are equally characteristic of the fertilized cell and lead to 

 the production of young organisms with full potential of vitality. 

 Disorganization and reorganization, although probably closely 

 related, are different in character and will be discussed separately. 



The destruction of the old macronucleus in Infusoria is one of 

 the most significant of the phenomena attending conjugation 

 (Fig. 139, p. 273). Here is an organ of the cell which is generally 

 regarded as intimately connected with metabolic activities of the 

 organism; which has functioned throughout vegetative life of the 

 race and has divided with each division of the cell. Yet at con- 

 jugation the macronucleus degenerates through hypertrophy and 

 fragmentation and the fragments are ultimately absorbed in the 

 protoplasm. The process is fundamentally the same in all ciliates 

 differing only in details. 



If the organization of a ciliate is dependent upon the specificity 

 of the proteins, carbohydrates, fats, salts and water which enter into 

 its make up, then this large bulk of nucleo-proteins distributed to 

 all parts of the cytoplasm must bring about a markedly different 

 matrix with which the new amphinucleus and its products are to 

 react. Zweibaum (1922) concluded that products of metabolism 

 during vegetative activity gradually poison the nuclear substances 

 so that both synthetic and oxidizing activities are weakened, but 

 at conjugation and with fragmentation of the macronucleus the 

 contained ferments are freed from their toxic bonds, and activity 

 is fully restored. The intake of oxygen is much greater after con- 



