The allelism at Henna locus in Drosophila melanogaster was iochemically investigated. From the experlmental, results Henna-recessive alleles seem to be pseudoallelic.
Red and yellow eye pigments extracted from male heads with 30 per cent acidic ethanol were estimated photometrically and compared with each other. Various genotypes resulting from allele combinations, regarding the eye pigment formation are in the following order:
+/+>+/Hn^r-1=+/Hn^r-3>Hn^r-1/Hn^r-1>Hn^r-1/Hn^r-3=Hn^r-3/Hn^r-1>Hn^r-3/Hn^r-3.
The separation of pteridines extracted from male heads and bodies was conducted by means of two-dimensional paper chromatography. Relative amounts of the separated pteridines were measured fluorometrically. A positive correlation between the amounts of sepiapterin (SP) and biopterin (BP) was recognized. A striking difference between the alleles was detected in amounts of SP and isoxanthopterin (IXP); the Hn^r-3 homozygotes had less IXP and more SP than the other genotypes.
The sepiapterin reductase, closely related to the conversion of SP to 2-amino-4-hydroxypteridine (AHP) was remarkably lower activity in Hn^r-3 than in the others. Hence, the accumulation of SP in the Hn^r-3 flies, especially in testes, was considered to depend upon the low activity of that enzyme.
A synthetic pathway of Drosophila pteridines was proposed from the experimental results. The Hn^r-3 gene apparently inhibits the process between dihydropteridine (YPH₂) and tetrahydropteridine (YPH₄), but the Hn^r-1 gene does not inhibit this step.

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In an attempt to obtain some information regarding heterografting of human cancer into rats, the presence and function of natural antibodies against the erythrocytes of human blood groups were studied in normal and pretreated rats from several strains. It was shown that the concentration of natural antibodies differ by rat strains, and that the natural antibody titers were comparatively lower in females than in males.
Both cortisone and X-rays act to suppress the production of natural antibodies for a certain period. The antibody formation is more storngly inhibited by X-rays than by cortisone. Cortisone acts to suppress the function of antibodies in circulating blood.

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Some histochemical observations of normal and abnormal ova in mature ovaries of mice (Swiss and D-240 albinos) were made at four stages of the oestrous cycle. The data obtained indicate that the primary and secondary normal ova in mature ovaries contain varying amounts of glycogen, that in a few individuals the ova contain no glycogen, and further that the atretic ova of large size always contain glycogen. Normal ova observed in both primary and secondary follicles showed a weak reaction to the test for RNA, suggesting that follicles contain a small amount of RNA. A few atretic ova undergoing maturation showed a reaction indicating the presence of a small amount of RNA.

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1. In order to ascertain how the cephalic complexes or the facet-increasing substances act on the development of the eye, the eye-antennal discs and the cephalic complexes taken out from the mature third-instar larvae (95 hours old after hatching at 25°C) of several eye-mutant strains of D. melanogaster were cultured in vitro in synthetic media with or without the facet-increasing substances.
2. The amount of the metamorphic hormone secreted from five cephalic complexes in a hanging-drop seems to be sufficient for the growth and differentiation of the eye-antennal discs. The cephalic complexes of several eye-mutant larvae seem to provide some unknown factors promoting the growth and differentiation which are characteristic to srveral eye-mutant strains.
3. Ammonium lactate and acetamide showed the significant effects upon the growth and differentiation of the eye-antennal discs in some mutant strains with the genetical back grounds of the wild type, cultured together with their own cephalic complexes, and upon those of the eye-antennal discs of Oregon-R cultured together with the cephalic complexes of these mutant strains.
4. Urea showed most marked effects upon the eye-antennal discs of several strains except Dp to promote the growth and differentiation of the wold type. Polypeptone also had effects similar to urea on all strains except Dp.
5. The eye- antennal discs of the Dp strain seems to be different from other eye-mutant strains in the responsibility to the cephalic complexes of the wild type, although the cephalic complexes of this strain seems to be similar to other eye-mutant strains in promoting the growth and differentiation of the eye-antennal discs of the wild type in media containing acetamide.

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