March 23, 1922] 



NATURE 



391 



critical. He finds the methods that have been 

 adopted by the council much too theoretical and too 

 purely scientific. He hopes much from the British 

 delegates, who also wish to see the work directed more 

 strictly towards the treatment of practical problems. 

 These reflections are very interesting. 



The first practical outcome of the fishery investiga- 

 tions is the report of the Plaice Committee. For 

 twenty years the question of the depletion of the 

 plaice-stock of the North Sea has been under in- 

 vestigation, but the study of the post-war conditions 

 has now hastened consideration of all the evidence. 

 The workers associated with the International Council 

 hold that a progressive impoverishment was in pro- 

 gress up to the year 191 4, and that the great restric- 

 tions on fishing due to the war arrested this decline 

 and restored the plaice population of the North Sea. 

 They ask that restrictions on fishing should be im- 

 posed so as to prevent the recurrence of the pre-war 

 overfishing. They recommend that the North Sea 

 between latitude 52° and 56° and within the Con- 

 tinental coast and the 12- or 15 -fathom contour line 

 be closed to steam trawlers and high-power motor 

 vessels for the whole or part of the year. They also 

 recommend transplantation of small plaice from this 

 closed area to the Dogger Bank. 



The fishing industry strongly opposes any restriction 

 on fishing outside the three-miles limit, and it is now 



evident that this objection will be fatal to the adop- 

 tion of the recommendations of the Plaice Committee. 

 Any restriction of this kind is bound to lead to 

 decreased profits or earnings at the time of its 

 imposition. As a rule traders take a very short view 

 of the circumstances in question, and are not inclined 

 to make personal sacrifices in order that future 

 generations of traders may obtain advantage. They 

 hold that the evidence available does not justify the 

 Government in accepting the recommendations noted 

 above. Would any evidence bring about such in- 

 dustrial altruism ? It is doubtful. In the present 

 case, however, the evidence that is available has 

 either not been published or it is presented in such 

 a way that it does not easily appeal to the owners 

 of fishing vessels. Obviously, such restrictions as are 

 indicated must be made and enforced against the 

 strong opposition of the fishing trade and with the 

 approval of the pubhc, and if that is to be so, the 

 fullest pubUcity should be given to all the data on 

 which the recommendations of the Plaice Committee 

 are based. It is understood, however, that the 

 passion for economy on the part of the Treasury 

 and Stationery Office is now preventing the publica- 

 tion of expensive official scientific reports, and, that 

 being the case, the attitude of the trade is, perhaps, 

 quite justifiable. J- J- 



Gametic and Zygotic Sterility. 



A FORM of pollen-sterility in which the anthers 

 -^ *- are aborted and the flowers fail to open is 

 described by Dr. Bateson and Miss Gairdner ( Journal 

 of Genetics, vol. 11, No. 3) in flax. Some flowers 

 produced a Uttle pollen, and when self-fertiUsed gave 

 rise only to male-sterile plants. This male-sterile 

 form appeared as 25 per cent, of the Fj of a cross 

 between a procumbent variety of Linum t9sitatis- 

 simum and the pollen of a common flax. Later 

 it was found that the sterility was determined by 

 the pollen of this flax, the procumbent variety 

 being genetically hermaphrodite on both the male 

 and female sides. 



In the same periodical Mr. Rudolph Beer makes 

 a study of the cytology and genetics of Fuchsias, 

 in which partial sterility of pollen and supernumerary 

 pollen-grains are well known to occur. He finds 

 that a pure species, F. arborescens, produces a large 

 proportion of sterile pollen, wliile a cross between 

 the distinct species F. pumila and F. alpestris shows 

 regular pollen-development and very few bad grains. 

 Such results have an interesting bearing on the 

 hypothesis that bad pollen is in itself a criterion of 

 hybridity. Some of the crosses result in " false 

 hybrids " similar to those obtained in strawberries. 



An interesting case in which ratios are altered 

 through zygotic sterility, or rather weakness in 

 development of a zygotic type, is described in the 

 same journal. Mr. Bungo Miyazawa describes a 

 dwarf type of barley which apparently arose as a 

 mutation, and without exceptional care is capable 

 of surviving only in the heterozygous condition. 

 Thus dwarf plants when self-pollinated gave 2 dwarfs : 

 1 tall, but by careful germination of the seeds the 

 homozygous type was enabled to survive, and was 

 found to be an extreme dwarf which was sterile, 

 producing no flowers. 



Prof. E. M. East [Genetics, vol. 6, p. 311) has 

 (lied the partial sterility in hybrids between 

 - cotiana rustica varieties and N. paniculata. Nearly 

 all the Fj plants resemble rustica, a few are almost 

 identical with paniculata, while many, expected com- 

 binations of the parental characters are missing. The 



sterihty varies from almost complete abortion of 

 pollen and seeds to nearly complete seed fertiUty. 

 This followed a condition of high sterility in Fj, in 

 which only about 3 per cent, of the ovules were 

 functional and only 35-55 per cent, of the seeds would 

 germinate. The pollen-sterility of F^ plants is even 

 higher, probably not more than o-i per cent, of the 

 possible grains from the pollen mother-cells reaching 

 functional maturity. Many break down in the 

 reduction divisions, and many apparently perfect 

 grains dry up when the anther opens. Nearly all the 

 F.^ plants show an increased fertility. The results 

 are explained in terms similar to Goodspeed and 

 Claussen's hypothesis of reaction systems. In brief, 

 certain chromosome combinations are non-viable or 

 produce offspring in which again only certain recom- 

 binations can survive. Prof. East suggests that 

 many cultivated plants have originated from similar 

 crosses in which a high degree of sterility has been 

 followed by greater fertility in certain surviving strains. 

 Further fight has been thrown on the sterility in 

 wheat hybrids by the fact that the different types of 

 wheat fall into three groups, which appear to have 

 multiples of 7 as their chromosome numbers. Dr. 

 Karl Sax (Genetics, vol. 6, p. 399) finds that the 

 pollen-grains show a corresponding increase in size, 

 the average relative volumes being 72 for Einkom, 

 94 for Emmer wheats, and 114 for T. vulgare. This 

 is to be expected with an increase in chromosome- 

 content. The results of many investigations indicate 

 that, in general, there is fertihty in crosses within 

 each group where the chromosome numbers are the 

 same, but more or less sterility in crosses between 

 forms belonging to different groups. Dr. Sax finds 

 that in fertile crosses of wheat species the Fj grains 

 (endosperm) are larger than in the parent--a 

 phenomenon of hybrid vigour — but in crosses which 

 are partly sterile the grains are small and wrinkled. 

 The degree of sterility may be determined by the 

 amount of grain set, or bv the amount of aborted 

 pollen. There is much variability in the size of pollen 

 in partly sterile F^ hybrids, which is probably due to 

 irregular chromosome distributions. R. R. G. 



NO. 2734, VOL. [09J 



