February, 1920] GENETICS 43 



was not destroyed. Newly formed leaves became white, as during the presence of the organ- 

 ism. Crossings made with not-disinfected flowers gave reciprocally (white male X green 

 female and white female X green male) only white plants (13 and 9j ; crossings of normal 

 flowers with flowers from an artificially infected inflorescence, green X white, only green (6); 

 white X green, only white (7) plants. Crosses of normal flowers with flowers of disinfected 

 white branches gave hybrids with intermediate leaf-form and spotted leaves (13). — Author 

 discusses possibility of vegetative segregation and of analysis of a chimera, and raises the 

 question whether mutation had been induced. Unfortunately author's plants were lost by 

 a fatality and pure cultures of the affecting organism have not been preserved. — M. J. Sirks. 



297. Van Someren, V. G. L. Melanism in Whydahs. Avic. Mag. 10: 40-41. Dec, 1918. 

 — States that Jackson's Whydah and another (Pentheria eques) tend to become black in cap- 

 tivity. The tendency is less noticeable in females than in males. — L. J. Cole. 



298. von Ubisch, G. Kritische BetrMchtungen zur Hypothese der primaren und sekundtt- 

 ren Koppelung. [Critical consideration of the hypothesis of primary and secondary coupling.] 

 Zeitschr. indukt. Abstamm. Vererb. 19: 193-201. 3 fig. June, 1918. — Review of papers by 

 Trow and by Bailey on primary and secondary reduplication according to the theory of Bate- 

 son and Punnett, in which the author fails to find that the formulas of Trow agree with the 

 observed facts in certain respects and in others are so general they do not distinguish between 

 the reduplication hypothesis and the chromosome hypothesis of Morgan. When three factors, 

 ABC, are coupled Trow's formulas allow for three different possibilities: — (1) There may 

 occur coupling between A and C and this coupling is always the same. (2) There may some- 

 times occur coupling between A and C and sometimes not. (3) The coupling between A 

 and C may vary in degree. The author points out the necessity for a closer agreement 

 between theory and fact and states the important features of the chromosome hypothesis. In 

 his own experience with barley 19 factor pairs are known, of which 10 up to the present have 

 been found to be coupled, most of these being in two groups. — D. F. Jones. 



299. Waardenburg, P. J. Aangeboren ooggebreken als oorzaak van blindheid en half- 

 blindheid. [Half-blindness and blindness due to congenital diseases of the eye.] Genetica 

 1 : 209-284. May, 1919. — A Dutch ophthalmological committee was appointed in December, 

 1916, to inquire concerning the causes of half-blindness and blindness of persons who were 

 treated b^ oculists in 1915 and 1916. It was found that 9.2 per cent of the 861 half-blind and 

 14.1 per cent of the 1444 blind were suffering from congenital diseases. Author, a member 

 of the Committee, has studied these cases (206). He found that 26.7 per cent was due to 

 buphthalmus (increase of pressure in the eye with resultant enlargement) ; 19.5 per cent to 

 atrophia retinae pigmentosa (degeneration of the nervous cells of the retina) ; 17.9 per cent to 

 microphthalmus and coloboma (insufficient development of the eye) ; 17.9 per cent to cataract 

 (cloudiness of the lens); 7.3 per cent to atrophia hervi optici familiaris (a disease that dis- 

 turbs the optic nerve generally after puberty); 5.3 per cent to albinism; 2.9 per cent to ani- 

 ridia (insufficient development of the iris with resulting or accompanying disturbances); and 

 2.5 per cent to achromatopsia (total color-blindness). — Report is divided into 16 chapters, the 

 first 8 of which treat the above-mentioned diseases separately. In order to appreciate 

 fully the results author has added observations made by himself and many foreign investi- 

 gators. Many interesting ophthalmological questions are mentioned; in congenital eye- 

 diseases it often happens that the centre of the retina, the most delicate part of the eye, 

 which is most highly organized, is affected. — Author considers heredity of paramount impor- 

 tance for all congenital diseases; achromatopsia and albinism appear to be recessive unit char- 

 acters; the other diseases are probably polyhybrid; however they do not result from crossing 

 of normal, but of abnormal genes. The abnormal variation of germinal factors may be due 

 to mutation, and this possibly means that the germ is disturbed by infection products (for in 

 many cases the author found syphilis among the causes). — In 115 families the parents were 

 19 times (16.5 per cent) blood-relations. In 75 families direct heredity of the diseases was 

 seen 5 (perhaps 7) times (aniridia, atrophia nervi optici, buphthalmus, cataract, coloboma 



