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My view is that the differentiation of these determinants for the two sides was due in the course of evolution to the different exposure to light, was of somatic origin, but once the congenital factors or determinants were in existence they were liable to mutation, and thus in the ambicolorate specimens there is a congenital tendency to pigmentation on the lower side, which would only be overcome by exclusion of light for another series of generations.
The brain weighed 1390 grams and showed little or no gross lesion, if we except a pigmentation of the right prefrontal region under an area of old pias hemorrhage. There was also a chronic leptomeningitis, with numerous streaks and flecks along the sulci, especially in the frontal region.
The dependence of pigmentation upon the sexual system is shown by the fact that irritation of the genital organs by disease will frequently suffice to produce a high degree of pigmentation. This may the neck, the trunk, the hands.
Pigmentation is common; the face becomes dusky red, the rest of the body a dark brown shade. This darkening is most marked in situations normally pigmented and in parts exposed to pressure of the clothes, such as the neck, axilla, and inner aspect of the arms, the extensor aspects being less marked than the flexor.
To any naturalist who has observed these fishes in the living state the protective resemblance of the pigmentation of the upper side is very evident, especially because, as in many other fishes and amphibians, the intensity of the colour varies in harmony with the colour of the ground on which the fish rests. But the utility of the white lower side is not so easy to prove.
Precocious maturity of the genital organs preceded and accompanied the pigmentation, but the hair was illy developed. Chloasma uterinum presents some interesting anomalies. Swayne records a singular variety in a woman in whom, during the last three months of three successive pregnancies, the face, arms, hands, and legs were spotted like a leopard, and remained so until after her confinement.
We now find that albinism in guinea-pigs shows an even greater range of variation, yet there can be no doubt of its fundamental unity as a Mendelian character, each grade of which is allelomorphic to every other grade and to normal pigmentation. Castle and Phillips, 1914, Publ. No. 195, Carnegie Inst. of Wash. Castle and Fish, Amer. Nat., Feb., 1915. Wright, S. Amer. Nat., March, 1915.
In some cases molluscum fibrosum is associated with pigmentation of the skin and with multiple tumours of the nerve-trunks. The small multiple tumours rarely call for interference. [Illustration: FIG.
Carrington and Crocker both record cases of permanent pigmentation following exposure to great cold. Gautier is accredited with recording in 1890 the case of a boy of six in whom pigmented patches from sepia to almost black began to form at the age of two, and were distributed all over the body.
The chief dispatcher looked at him steadily a long moment before answering. "I imagine you will find people of various shades all over town, including those allegedly white. Was there anyone in particular you were interested in or are you solely concerned with pigmentation?" "Why, you goddam " I thought it advisable to prevent a possible altercation.
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