368 



4. Fortpflanzungslehre. 



grün), worin die Probiergläschen mit Sperma versenkt waren und direkter 

 Sonnenbestrahlung ausgesetzt wurden. Die Abtönung der Farbe geschah nach 

 Augenmaß. 



Das Ergebnis war folgendes: die den roten Strahlen ausgesetzten Sper- 

 matozoen überlebten Spermatozoen in gelben, diese Spermatozoen in blauen 

 und letztere überlebten Spermatozoen in violetten Strahlen. Die Vergrößerung 

 der Intensität des Farbtones verstärkte die schädigende Wirkung. 



E. Paukul (Dorpat). 



1014) Harris, J. A. (Washington, U. S. A.), On the Correlation bet- 

 ween somatic characters and fertility: illustrations from the 

 involucral whorl of Hibiscus. 



(Biometrika 8,1/2. p. 52-65. 1911.) 

 Finds that the correlations between the number of bracts and number 

 of ovules or seeds, though sometimes statistically significant, are uniformly so 

 small that no practical biological importance is to be attached. 



Doncaster (Cambridge). 



1015) Berke, B., Ein Bandwurm im Hühnerei. 



(Kosmos 6,3. p. 116. 1911.) 

 Im Dotter eines Hühnereies fand sich ein bereits vollkommen ausgebildetes 

 Exemplar von Taenia solium, das neben dem Scolex noch zwei Glieder aufwies. 



P. Schulze (Berlin). 



1016) King, H. D., Studies on Sex-Determination in Amphibians. 

 IV. The Effects of External Factors, Acting Before or During the 

 Time of Fertilization, on the Sex Ratio of Bufo lentiginosus. 



(Biol. Bull. 20,4. p. 205—235. March 1911.) 

 (1) The Influence of Alcohol on the Sex Ratio of Bufo. 

 Batches of eggs from the same female were placed with sperm from the 

 same male in alcohol Solutions of the following strengths: 10, 5, 2, 1, 0,5, 

 0,25, 0,13 per cent. In each case the eggs remained in the Solution for one 

 half hour and were then transferred into fresh water where they continued 

 their development. None of the eggs that were subjected to the 10 per cent 

 and the 5 per cent alcohol segmented. The following table gives the history: 



Eggs fertilized in Solutions of Alcohol. 



Control 



210 



134 



65 



69 



54,81 



The sex ratios obtained are very uniform with deviation less than five 

 per cent from that found in the control lot. Statistics of some 10,000 young 

 toads show that in the normal sex ratio in Bufo there is a slight excess of 

 females varying from 51 to 56 per cent. It follow from the sex ratios ob- 

 tained in this series of experiments that alcohol of the strengths used and 

 for the time it acted has not influence on the determination of sex in Bufo. 



(2) The Influence of the Spermatozoan on Determination of Sex in Bufo. 



