38 GENETICS [Bot. Absts. 



264. Kirkham, William B. The fate of homozygous yellow mice. Jour. Exp. Zool. 28: 

 125-135. 2 fig. May 20, 1919. — In prenatal life of animals two crises occur, one at implan- 

 tation and one at parturition. Latter is apparently not significant in fate of homozygous 

 yellow mice as the dead young would have been observed if they occurred in anything like 

 the expected number. Mouse ovum has food enough to maintain itself up to blastula stage. 

 Factors are here relatively stable. Much less stable set of factors governs implantation for 

 cleaving ova and blastulas of white mice average over seven per pregnant animal while num- 

 ber of young in litters average less than five. After implantation development is almost 

 always normal up to birth, in mice of all colors. As regards implantation, two sets of factors 

 exist, maternal and embryonic. Corpora lutea stimulate proliferation of uterine mucosa, a 

 necessary antecedent to implantation of blastulas. Mouse blastula stimulates further swell- 

 ing of uterine connective tissue and dissolution of this along with the epithelium, thus supply- 

 ing food to embryo. Lactation inhibits both sets of stimuli. Various factors may explain 

 failure of some blastulas to implant in white mice. Time of ovulation from last parturition, 

 time of fertilization, rate of cleavage, and time of implantation is same for all embryos, whites, 

 homozygous yellows and heterozygous yellows, showing that eggs with yellow factor undergo 

 maturation and fertilization even when entered by yellow-bearing sperm. Abnormalities of 

 homozygous yellow appear first in morula. At implantation they plasmolyze and are phago- 

 cytized, but nevertheless effect uterine changes, thus differing from abnormal embryos of 

 non-yellow mice. There is in addition to parental abnormality (tendency in yellow of both 

 sexes to fatness and sterility at early age) an inherent weakness in homozygous yellow em- 

 bryos. It may be possible to transplant ovaries of yellow to non-yellow and thus to obtain 

 homozygous yellow offspring by avoiding abnormal maternal factors. Proportion of degen- 

 erate embryos from yellow by yellow is 29+ per cent, very close to Mendelian expectation. 

 —P.W. Whiting. 



265. Kuster, Ernst. Ueber Mosaikpanaschierung und vergleichbare Erscheinungen. 

 [On mosaic variation and comparable phenomena.] Ber. Deutsch. Bot. Ges. 36: 54-61. 1918. 

 — Mosaic pattern is of very common occurrence among plants. When spots are large they 

 are called marbled, but dotted or pulverulent if spots are very small. Not only absence of 

 chlorophyll but also absence of anthocyan may give rise to mosaic pattern (e.g., Coleus 

 hybridus hort.). Shape of the spots, their sharp limitation and often also arrangement of their 

 cells suggest that they took their origin from one initial cell, which in turn arose by an unequal 

 division. There are two different ways in which such an unequal division can be imagined to 

 take place. In agreement with ideas of Weismann one daughter cell might be deprived of 

 a certain part of the protoplasm or nuclear substance, in which case the cell will never be able 

 to show again the lost qualities. Or the daughter cells might differ only in a physiological 

 sense, not in a morphological one, reacting in a different manner to external influences, in 

 which latter case reversion may be involved. Writer believes that divisions of first type have 

 been recorded among Protista, whilst divisions of the second type occur, e.g., when mutants 

 are produced in cultures of bacteria, which afterward show regressions to the mother type. 

 As to the phenomena of mosaic variegation he assumes that the unequal divisions are of the 

 second type and thinks possible that within white spots, green tissue might reappear. — 



K. Boedyn. 



266. Lehmann, Ernst. Ueber reziproke Bastarde zwischen Epilobium roseum und parvi- 

 florum. [On reciprocal crosses between Epilobium roseum and E. parviflorum.] Zeitschr. 

 Bot. 10: 497-511. 7 fig. 1918. — Author crossed E. parviflorum with E. roseum in both direc- 

 tions and obtained two wholly different hybrids, the first of which he called "E. rigidum," 

 the second "E. curvatum." E. curvatum is an intermediate type, with some resemblance to 

 E. ■parviflorum, whilst E. rigidum, a more sterile type than E. curvatum, looks rather like 

 E. roseum. According to the fact that in Epilobium unlike reciprocal hybrids were discovered 

 this genus becomes of great interest especially in connection with recent researches on Oeno- 

 thera. — K. Boedyn. 



