Nuclear DNA content of Ae. squarrosa, natural Emmer and natural and synthesized Dinkel wheats, in addition to Tetra Canthatch (AABB) which was extracted from common wheat, was measured Feulgen-microspectrophotometrically using PMC's at first prophase or pollen tetrads.
A significant amount of variation in DNA content per nucleus was observed among seven strains of Ae. squarrosa, indicating intraspecific differentiation accompanied by gain or loss of genetic material in this diploid species.
DNA content per nucleus of the extracted tetraploid (Tetra Canthatch) was the same as those of present-day natural Emmer wheat; no appreciable quantitative change in nuclear DNA of the A and B genomes of common wheat seems to have taken place during at least the past seven thousand years, in spite of considerable genetic changes that have occurred.
Two natural and six synthesized hexaploids had similar DNA content that was approximately equal to the sum of those of their parents.
Evidence concerning variation in nuclear DNA content of higher plants was reviewed and quantitative relationships between diploid and polyploid species in DNA content was discussed in relation to its evolutionary significance.

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The conditions for Giemsa-band formation in air-dried chromosomes of HeLa cells and FL cells were examined in detail. When chromosome preparations were stained immediately after air drying, Giemsa staining alone, if the staining solutions were prepared with saline solutions of which pH values were higher than 6, produced bands. It seems that a variety of pretreatments including trypsin treatment so far reported are not essential conditions for band formation but rather promoting ones. Brief refixations with formalin, glutaraldehyde or picric acid solution prior to band inducing procedures markedly prevented band formation. Basic dye itself appeared to act to prevent band formation, since chromosomes once stained with Giemsa or toluidine blue became extremely reluctant to show bands. It seems very likely that the structural lesion of chromosomal porteins would be an indispensable triggar to induce banded structures.

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In order to obtain large quantities of metaphase chromosomes, we have established the optimum conditions for obtaining a large mitotic cell population from cultured Chinese hamster Don cells (CH-Don-13 clone) by two treatments with a combination of colcemid and harvesting techniques: after pretreatment of a given number of CH-Don-13 cells with 0.025μg/ml of colcemid for 6 hours, the first mitotic cell population was collected by harvesting and the remaining cell population was again treated with 0.025 μg/ml of colcemid for 4 hours; then the second mitotic cell population was collected by harvesting and combined with the first mitotic cell population kept at 0° to 4°C. Mitotic cells obtained by this method showed no significant biological or cytological damage, and the chromosomes isolated from these cell populations were morphologically intact.

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Two kinds of modifiers for SD system on the second chromosomes, Ac(SD)-like and St(SD)-like were examined on a natural population, Odate, Japan. Among 21 isofemale lines six lines carried Ac(SD)-like and five beared St(SD)-like modifiers. None of the second chromosomes examined beared both of these two kinds of modifiers simultaneously.
The effects of these modifiers as a suppressor or a enhancer of SD were not so stable and were differently affected by different Recombinant-SD, i.e., RSD₁and RSD₂. In general, the k values of RSD₁/Ac(SD)-like or RSD₁/St(SD)-like males were higher than those of RSD₂/Ac(SD)-like or RSD₂/St(SD)-like males respectively. These results probably came from the different strength of distortion in these two SD strains.
From the results of mapping experiments, Ac(SD)-like was located near cn locus, and it was estimated to be Ac(SD) itself. The results of fecundity experiments also supported this conclusion.
A St(SD)-like modifier which was located on an inversion free second chromosome seemed to consist of at least two elements. Therefore this St(SD)-like was concluded not to be St(SD). On the other St(SD)-like associated with NS inversion, any direct genetic analysis was impossible.

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Changes during development and tissue or organ specificities of α- and β-esterase zymograms of D. virilis were studied by thin layer agar gel electrophoresis. Quantitative changes in α- or β-esterase activities were also examined through the period from first instar larvae up to about the two-week old flies.
Both analyses indicated that the activity of α- and β-esterases was high in early third instar larvae and adult flies, remaining at low levels during the period around pupation, although slight differences in developmental profiles were found between α- and β-esterases. No specific bands were noticed in any particular developmental stage.
Localization among various body parts was not the same for α- and β-esterases. Both esterases appeared in hemolymph as well as in whole fly homogenate. But in the homogenate of gut only α-esterase bands were found and, in contrast, only β-esterases were detected in the zymogram of head homogenate.

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Differences among allelic isozymes at Est-α or Est-β locus of D. virilis, as well as the differences between α- and β-esterases, were studied by different immunological techniques; Ouchterlony double diffusion, immunoelectrophoresis and immunochemical cross-reaction. Antisera were made against two different antigenic preparations, Est-α⁸ and Est-β^B isozymes. The results of all immunological tests indicated coincidentally that allelic variants of α- or β-esterase were immunologically identical but these two groups were completely distinct concerning antigenic determinants.
Neither anti-α⁸ nor anti-β^B serum reacted with “null” fly (silent allele homozygote α⁰β⁰) extract. No precipitin line was obtained for the null strain in either Ouchterlony nor immunoelectrophoretic tests. The analyses of adsorption tests demonstrated that the silent alleles examined (α⁰ and β⁰) did not synthesize any cross-reacting proteins. In similar ways it also became apparent that the β^D' strain which gave a very faint band in the esterase zymogram produced a very little amount of cross-reacting materials, only between one eighth and one fourth of the other β-esterase variants.

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Genetical and physiological analyses were undertaken in interspecific incompatibility between Nicotiana alata and N. langsdorffii. Experiments were also done to elucidate the relationship between self-incompatibility and interspecific incompatibility.
There is bilateral interspecific incompatibility between N. alata and N. langsdorffii though the combinations with N. langsdorffii as female show higher compatibility than its reciprocal one. It is supposed that the gene which controls interspecific incompatibility is not a definite gene such as S in self-incompatibility, but is polygene. Though pseudo-self-compatibility in N. langsdorfjii is probably also controlled by polygene, plygenes participating in self- and interspecific-incompatibility are different each other. In both incompatibilities, the growth rate of incompatible pollen-tube is much slower than in compatible combination, and fertility increases by bud pollination. To understand these facts, hypotheses are proposed in the present paper.

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