776 Kemp.—On the Question of the Occurrence of 
elusion. Nemec insisted that the large lobed, or ‘bridge’ nuclei, which 
Wasielewski had supposed to be in amitotic division, really arose through 
arrested mitosis, this arrest resulting in incomplete separation of the two 
groups of chromosomes, which consequently formed, in late telophase, a 
lobed nucleus easily mistaken for one undergoing amitotic division. He 
further stated that the chloral hydrate acted upon the achromatic structures 
of the cell, attacking and dissolving the fibres normally visible in division, 
and so arresting the movement of the split chromosomes to their respective 
poles ; also that the two groups of chromosomes tended to fuse together 
again in one mass, and that the single nucleus so formed contained double 
the normal amount of chromatin and broke up, on subsequent division, into 
a number of chromosomes twice that characteristic of the tissue in question. 
The interest of Nemec’s work, however, rests not so much upon his 
treatment of the problem of amitosis, as upon the theory of the occurrence 
in somatic cells of heterotypical-reduction, which he brought forward in 
explanation of the fate of the above tetraploid nuclei. Nemec pointed out 
that after a period of some hours the latter disappear, and suggested three 
possible ways in which this disappearance might occur. (1) That the large 
tetraploid cells pass over into the permanent tissue, their nuclei becoming 
inactive. (2) That should the tetraploid number occur in initial cells, 
these having lost the power of frequent division through the action of the 
chloral hydrate, their function as initial cells is taken on by their neighbours. 
Or (3), that by a sudden automatic process of reduction, very similar to the 
heterotype reduction occurring in spore mother-cells, the tetraploid number 
of chromosomes is reduced to the diploid number. Nemec himself adopted 
the third of these hypotheses on the following grounds. He had observed 
certain curious tetrad-like figures in the pea during recovery from treatment 
with chloral hydrate, and believed these to be an indication of the occurrence 
of two divisions in immediate sequence, comparable to the heterotype and 
homotype divisions seen in sporogenous tissue. Again, he had found that 
the number of tetraploid figures in roots fixed, for example, after twenty- 
seven hours’ growth subsequent to treatment with the drug, was markedly 
less than in those fixed at an earlier stage of the experiment, and that at 
forty-eight hours such figures had entirely disappeared. Finally, he had 
observed one abnormally large cell, containing, not the tetraploid, as might 
have been expected from its size, but the normal number of chromosomes ; 
and he held this normal number to have arisen by reduction. 
Nemec maintained that such a reduction-process, occurring as he 
believed in somatic tissue, as a result of the action of chloral hydrate, 
was a reversion to a primitive capacity of reduction, innate in somatic cells, 
and from which he suggested has been evolved the elaborate reduction- 
process seen in the sexual cells of the higher plants and animals. ‘ Man 
konnte schliessen, dass die Fahigkeit zur Kernverschmeizung und zur 
