NOTES AND ABSTRACTS. 



823 



plant, as Wittmiack has suggested, and certainly not the 

 origin of the domestic potato, as Sutton has suggested. If it be a 

 hybrid, as Paton thinks, then it has probably been derived from two 

 wild species and has not *S'. tuherosum as one of its parents. It 

 appears, from the experiments detailed, to be somewhat closely related 

 to S. Ma^lia. The papel^ is illustrated by excellent plates.— F. J, C, 



Potatos, Male Sterility in, a Dominant Mendelian Charac- 

 ter; with Remarks on the Shape of the Pollen in Wild and 



Domestic Varieties. By Dr. E. N. Salaman (Jour. Linn. Soc. 

 xxxix. 1910, pp. 301-312). — The author found that contabescence of 

 the anther — a state in which the anther is more or less shrivelled up 

 or aborted and contains no pollen — is a dominant hereditary character 

 in the Potato. Pale heliotrope potato-flowers have always been found 

 to be sterile, and, so far as yet investigated, heterozygous as regards 

 sterihty. 



A high percentage of living pollen-grains has only been found in 

 anthers containing abundance of pollen, but abundance of pollen in the 

 anther does not always signify a high percentage of fertile pollen -grains. 



Starting with two lines each possessing a high standard of fertility 

 among its pollen-grains plants arise which have a tendency towards 

 the production of sterile pollen, and in a subsequent generation these 

 produce individuals with complete male sterility as regards " quality " 

 of pollen. 



The normal pollen-grain of both wild and domesticated potatos, 

 when dry, is oval. Irregular grains are immature or dead grains. 

 When water is added all the oval grains at once become circular, and 

 are seen to be filled with a finely granular substance, while three 

 apertures for the exit of pollen-tubes are at once obvious. The 

 irregular grains retain their irregular shape and are seen to be empty 

 or to contain a small bubble of air. These differences in shape were 

 found in the wild species as well as in the .cultivated, but the author 

 has met with examples, such as the first cross between the cultivated 

 varieties Congo and Flourball (and of the same cross), as well as 

 several other cases, in which the pollen was quite as perfect and more 

 abundant fFan in any wild type. On the other hand, the majority of 

 the commercial potatos have but little pollen, and that little irregular 

 and sterile. Comparative tables are given in the paper in which the 

 pollen of cultivated and wild types are compared. From these it is 

 seen that there is no essential difference between the two types. 

 Solanum tuherosum (a wild type) possesses the most completely oval 

 pollen-grains, but even so it is with difficulty to be differentiated, in 

 respect of purity and shape, from the first cross between Congo and 

 Flourball (both cultivated varieties). The wild S. Commersonii is not 

 so pure to the oval type of pollen as the domestic varieties Flourball 

 or Eeading Eusset. 



The later in the season the more likely is the quality of the pollen 

 to deterior^at^. — R. B. 



