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Sidney I. Kornhauser 
to be many raore units which behave independently in inheritance than 
there are chromosomes in the germ cells, to say nothing of the disparity 
in the number of chromosomes in nearly related animals and plants. 
If, then, each chromosome bears a number of determinants, there must 
be some mechanism for the redistribution of these determinants other 
than a mere chance Separation of the diploid complex of chromosomes into 
two unlike groups. 
Many phenomena exhibited in the conjugation of the chromosomes 
have been described in the past ten years and many theories to explain 
their relation to heredity have been propounded. Theory has often 
run far ahead of established fact, and the opponents of the chromosomal 
basis of heredity have not failed to bring this state of affairs to light. 
The whole question rests mainly on the rnethod of syndesis, the formation 
of the tetrads, and the meaning of the maturation divisions. 
The wärmest controversies have arisen over the rnethod of the origin 
of the double loops seen in the bouquet stage. In spite of the vehement 
objections of those who maintam that this doubling is nierely a longitudhial 
division (Me\t;s ’08; Goldschmidt ’08b; Haecker ’IO, ’ll), there has 
been a steady increase in the data, gathercd from both zoölogical and 
botanical research on diverse and often widely separated forms, going 
to show that the double threads result from the side-by-side union of 
the chromosomes in pairs. Winiwarter et Sainmont (’09) have main- 
tained the position taken by "Winiwarter (’OO), that in mammals it is 
parasyndesis which takes place in the oöcytes. Their view differs from 
that of the Schreiners — who are also strong adherents of parallel 
conjugation of the chromosomes and have described this rnethod of 
syndesis for many invertebrates as well as vertebrates (’06a— ’08b) — 
as regards the degree of intimacy of the union between chromosomes. 
Winiwarter et Sainmont Claim an absolute fusion of the conjugants, 
and in this they are supported by Bonnevie (’ll). The Schreiners, 
on the other hand, maintain that the interchromosomal line remains 
throughout the period of the lateral approxiniation of the threads and 
that the line of Separation in the strepsistene stage corresponds to the 
interchromosomal line of the zygotene stage. The facts gathered from 
the study of Enchenopa support the view of the Schreiners. 
Gregoire (’05, ’09, ’IO) has upheld the rnethod of syndesis and 
reduction described by the Schreiners and has attempted to apply this 
rnethod (parasyndesis followed by hetero-homeotypic division) universaUy 
to both plants and animals. The first division is reductional and se- 
parates the chromosomes which paired side by side; the second division 
