The Gravitation Constant. I BEG to point ant t_hat at the end of the article on pp. 127-128 of NATlTRE, relatrng to my researches on the gravitation constant, there is a misprint. The " oscillation" result for 1892 sh?nld be 5 •5~3 instead of 5 •520. fh e error 1s not great, but by correcting it a much better concordanc~ appears between the four principal values.
We think it desirable, in the interests of clearness, to explain the meaning of the nomenclature that is employed in this memoir in connection with the “reduction “divisions.
In 1903 and 1904 one of us, in conjunction with Professor Farmer, ■described the maiotic process in a variety of animals and plants.* From the observations then accumulated it was in the first place shown that what we termed the maiotic process appears to be the same throughout the animal and vegetable kingdoms. In the second it was pointed out that the general scheme we were able to formulate was in accord with the particular descrip tion of the metamorphosis given by Korscheltf for Ophryotrocha as long ago as 1895, as well as with the account of the same change in some amphibia given by Montgomery]; in the same year as ourselves.According to this conception of the maturation process, the reduction in the number of chromosomes to one half is brought about by a pairing of somatic chromosomes which takes place in the prophase of the first maiotic (heterotype) divisions. In this way we have in some mammals, for example, 16 pairs of chromosomes in the place of 32 single elements.These chromatic gemini, as we propose to call them, go on to the sp in the same way as ordinary premaiotic or somatic chromosomes. But during the division each of the respective gemini separate into the two component p arts; so that in the cases of mammals above referred to there are 16 premaiotic chromosomes distributed to each daughter cell.According to this view it would appear that during the first maiotic division no longitudinal fission of the chromosomes composing the gemini comes into play, and the longitudinal split which is visible in the spirem figure only effects that incomplete fission of the daughter elements first observed by Flemming in the diasters of the first maiotic division in amphibia (see fig. 22).In this way the longitudinal split of the thread which takes place in the spirem stage only becomes completed and effective during the second * Cf. Farmer and Moore, 'Roy.
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