. Genetics in relation to agriculture. Livestock; Heredity; Variation (Biology); Plant breeding. VARIATION 29 In experiments on lower animals, , the protozoa, the same difficulty is met with as has been encountered in bacteria and yeasts, in that it is manifestly impossible to distinguish between somatic and germinal variations. Moreover, in most of these experiments, as with most of those on higher animals, the necessary conditions for rigid scientific analysis have been lacking. Either the same strain as was subjected to artificial conditions was not grown for comparison under natural co
. Genetics in relation to agriculture. Livestock; Heredity; Variation (Biology); Plant breeding. VARIATION 29 In experiments on lower animals, , the protozoa, the same difficulty is met with as has been encountered in bacteria and yeasts, in that it is manifestly impossible to distinguish between somatic and germinal variations. Moreover, in most of these experiments, as with most of those on higher animals, the necessary conditions for rigid scientific analysis have been lacking. Either the same strain as was subjected to artificial conditions was not grown for comparison under natural condi- tions or else the conditions themselves were not sufficiently well con-. FiG. 12.—Leaf and cluster of fruit of Red Cherry tomato of the second generation (right); same of the sixth generation (left) of continuous treatment with excessive amount of dried blood. (Photo by T. H. White.) trolled to permit of certain analysis. It is interesting to note that the pomace fly, Drosophila ampelophila, which has produced more mutations so far as we know than any other organism, was subjected to the effects of ether on a grand scale and under controhed conditions by Morgan, but that not a single mutation was observed to result from this treat- ment. However, mutations have subsequently appeared again and again in cultures of "wild" flies not only of this species but also of other species of Drosophila. Thus it appears that germinal variations fre- quently occur independently of external stimuli. It also seems that a tendency to produce mutations may be inherited-. Digitized by Microsoft®. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Babcock, E. B. (Ernest Brown), b. 1877; Clausen, Roy Elwood, 1891-. New York, McGraw-Hill; [etc. , etc. ]
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