Vietnam or Thailand ? Vote for the TOP Country of the Week !
Updated: May 3, 2025
These "eating yelk-cells" are found in large numbers in the food-yelk of the Selachii, especially in the yelk-wall the border zone of the germinal disk in which the embryonic vascular net is first developed. The nuclei of the merocytes become ten times as large as the ordinary cell-nucleus, and are distinguished by their strong capacity for taking colour, or their special richness in chromatin.
Which of these various bodies shall we continue to call protoplasm? Shall it be the linin, or the liquids, or the microsomes, or the chromatin threads, or the centrosomes? Which of these is the actual physical basis of life?
These results tend to show that factors are not indivisible units, and segregation is rather the difficulty of chromatin or germ plasm from different race uniting together. It must be remembered that the fertilised ovum which forms one individual gives rise also to dozens or hundreds or thousands or millions of gametes.
Hence, if the number of chromosomes in the next generation is to be kept equal to that in the last generation, this egg cell must get rid of a part of its chromatin material. The result is that the egg has now the normal number of chromosomes for the ordinary cells of the animal in question.
Further, it will follow that if this dormant undifferentiated chromatin should start into activity and produce a new individual, the new individual thus produced would be identical in all characters with the one which actually did develop from the egg, since both individuals would have come from a bit of the same chromatin. The child would be like the parent.
The typical form appears to be spherical or nearly so; but from this typical form they may vary, becoming irregular or elongated. The form and shape of the chromatin thread differs widely. The nucleii differ also in the number of nucleoli they contain as well as in other less important particulars.
They demonstrate also the apparent chance nature of the phenomena of inheritance. To my mind the most striking and significant result in this field is the demonstration that a particular chromosome or chromatin mass determines a particular character of an adult organism, which is quite a different matter from the reference of all the hereditary characters to the chromatin as a whole.
Word Of The Day
Others Looking