Learn More
HE limitation in the penetrating power of electrons is one of the most T serious obstacles in the study of chromosomes by electron microscopy. Chromosomes are generally larger than 0.2p in diameter and are nearly opaque to electron penetration. At various stages of the nuclear cycle, however, chromosomes change their size and shape. Dividing chromosomes are(More)
ETEROZYGOSIS for recessive mutant genes, some of which are H lethal or semilethal in homozygotes, is very common in natural populations of Drosophila. In D. pseudoobscura, from fifteen percent (in the Death Valley region of California and Nevada) to thirty percent (in Mexico and Guatemala) of the third chromosomes contain lethals or semiIethals. DOBZHANSKY(More)
  • 1