THE REDUCTION OF THE CHROMOSOMES 



of considerable significance, not all investigators concur in this opinion. 

 That synizesis is an artifact due t<» Faulty fixation is an interpretation 

 which, though it may be justified for certain cases in which the contrac- 

 tion may be very slight or absent, is doI of general application. Fixa- 

 tion often serves to accentuate the appearance of contraction, bul the 

 characteristic synizesis figure has been observed widely enough in faith- 

 fully preserved, and even in living material to make it evident that we 

 are dealing here with a normal feature of the heterotypic prophat It 

 may not, however, be of universal occurrence. 



R. Hertwig (1908) came to the conclusion, as a deduct ion from his 

 theory of the nucleoplasmic relation, that the phenomena of the hetei 

 typic prophase represent an abortive mitosis: the disturbed nucleoplasmic 

 balance is restored to the normal by a multiplication of chromat in without 

 an actual mitosis, the process taking the form of the changes peculiar to 

 the heterotypic prophase. This view of Hertwig, which was denied by 

 Gregoire (19096), is supported by Kingsbury and Hirsch (1912), who 

 state: 



"According to this view, on the one hand, synizesis represents 'an attempt 

 on the part of the spermatogonia to divide again — which fail-: while on the other 

 hand, the reputed conjugation of chromosomes occurring at about this time i- 

 but the imperfect fission and subsequent fusion of daughter chromosomes of Buch 

 abortive division." 



The above quoted authors regard synizesis and synapsis as indicat i' 

 of the onset of degeneration. In this conclusion they are supported by 

 Kingery (1917), who, in his investigation of the white mouse, finds 

 synizesis in the primitive germ cells which degenerate, but not in the 

 definitive germ cells. Observations of a similar nature were made by 

 Wodsedalek (1916) in the mule. If, as Kingery (1917) and Popoff 

 (1908) point out, the "heterotypic' 1 changes are due to degeneration, 

 they should be found in abnormal somatic cells. Marcus 1907 . in 

 fact, had observed a contraction similar to that of synizesis preceding 

 degeneration in the cells of the thymus gland. Nemec * r.»o:>i and Kemp 

 (1910) also found that in the cells of roots treated with chloral hydrate 

 the nuclei come to have an abnormally high number of chromoson 

 ("syndiploid nuclei"), this number, according to Nemec, being gradually 

 restored to the normal during tin 1 subsequent mite--, which -hew 

 phenomena of a heterotypic nature. Strasburger 1 191 1 I, while agreeing 

 with Nemec that the syndiploid condition gradually disappears, denied 

 that any truly heterotypic phenomena are concerned. The 'hetei 

 typic" changes observe* 1 by Xemee he held to be only peculiar vegetative 

 mitoses with a superficial resemblance to genuine reduction divisioi 



Nemec's conclusion regarding a reduction in chloralized vegetative 

 cells is also contradicted by Sakamura (1920), who has made a particu- 

 larly exhaustive study of these phenomena. Sakamura finds that a 



