BRIEF REPORTS

SUMMARY There is debate about the ideal diagnostic procedure for uri-nary tract infections (UTIs) in general practice. The aim of this study was to evaluate nitrite and leucocyte esterase strip test procedures in general practice patients, and to relate the results to the decision of the general practitioner to prescribe antibiotic therapy. A total of 292 female patients from eight general practices in the Maastricht area, who were aged 12 years or over with complaints suggesting UTI, were included in the study. All eight practices tested fresh urine samples using the nitrite strip test, and seven also used the leucocyte esterase strip test. The positive predictive value of the nitrite test was greater than the leucocyte test. Antibiotic therapy was nearly always prescribed when either or both of these tests were positive. Bacterial culture was positive in 159 (59%) cases, although treatment was started in 70 (27%) cases where there was an absence of significant bacteruria. It was found that the choice of agent used to treat the patient was related to the antibiotic susceptibility of the uropathogens that were isolated.

A. JOSEFSSON: Tetraploid turnips a progress in Swedish I' 0 0 tel' 0 p b I' e e din g. At the Swedish Seed Association, tetraploids of most field crops are produced by colchicine treatment. Most successful among these new artificially induced autotetraploids are those which have a rather low number of chromosomes, are cross fertilizable and where the vegetative parts are used. Thus, root crops have been a good object for chromosome doubling experiments. This is especially the case with turnips. The diploid chromosome number is 2n=20. It is a cross fertilizer and the crop is grown to obtain the roots. The tetraploids often have a high vegetative production. The dry matter content, however, is somewhat low, but the yield of dry matter is high. The artificial autotetraploids have, as a rule, a decreased fertility, but the yield of seed is not of the same importance to the root crops as to other farm crops.
Doubling the chromosome number of some varieties of turnips was started by Dr. ALBERT LEVAN about fifteen years ago. In the spring of 1946 some tetraploid seeds of the three varieties Bortfelder, Yellow Tankard and Ostersundom were sown for the first time in a comparative test with diploid and tetraploid turnips. In 1951 a seed stock of tetraploid turnips was handed over to the General Swedish Seed Company for propagation and in 1953 this stock was marketed under the name of »Svalof''s tetraploid Sirius turnip».
The breeding and testing of the tetraploid turnips have been carried out in close co-operation between the main station and the different branch-and sub-stations of the Seed Association in districts where turnips are normally grown. A special breeding program of the tetraploids was started at the Jamtland branch station as well as the Svalof station. Crosses have been made at two different branch stations between all tetraploid strains available. The progenies of these »rnass crosses» have been tested in field trials and have been shown to give a very high yield of roots and dry matter. Some crosses between tetraploid strains of Bortfelder, Yellow Tankard and Ostersundom have shown excellent results. The tetraploid Sirius is an F, variety derived from crosses between some strains of these three different types.
In breeding tetraploid turnips two methods are used. One of them tends to produce tetraploid strains quite similar to the diploid mother strains as to type and colour of root. The other method, as mentioned above, is to produce a very heterozygous stock. It is possible to get four different alleles at each locus in one and the same plant. Thus, theoretically, there is a greater probability that a tetraploid will be heterozygous at any particular locus than a diploid. Thus, tetraploid plants can utilize the effect of heterozygosity better than diploids. In the trials described below, extending over 7 years (1948)(1949)(1950)(1951)(1952)(1953)(1954) at 7 different stations, tetraploid strains have been compared with the corresponding diploid mother strain; and »rnass crossed» material, especially the variety Sirius, is compared with the highest yielding of the constituent diploid strains. All the strains have not been tested each year owing to lack of seed.
All the tetraploids had a good and well-formed root but the dry matter content of the root was somewhat lower in tetraploids than in diploids. The dry The ditTerence in dry matter in the last comparison corresponds to t = 3,20**; 0,01> P> 0,001, matter yield, however, was higher and the tetraploids seemed to have a more rapid development than the diploids. The tetraploids also seemed to maintain their superiority under unfavourable as well as under favourable conditions. As shown in Table 1, tetraploid Bortfelder has been compared with diploid in 38 trials. The tetraploid has usually given 15 per cent higher yield of roots and 5 per cent higher yield of dry matter than the diploid. The dry matter content, however, was 0,8 per cent lower in the tetraploid crop. The tetraploid strain of Yellow Tankard tested is very high yielding. The root yield was 37 per cent and the yield of dry matter was 22 per cent higher in this tetraploid than in the corresponding diploid material. The tetraploid strain of Ostersundom has not given so good results. The figures were 9 and 5 per cent, respectively. In some trials this tetraploid has yielded less than the mother strain. The yield of tetraploid Ostersundom fluctuated more than that of the other tetraploids.
Sirius has been tested in 33 trials and has outyielded Bortfelder in dry matter yield by 22 per cent and Ostersundom by 11 per cent. The content of dry matter was only 8,7 per cent while the diploid standards had 10,0 and 9,1, respectively. The roots of Sirius turnips are medium long and are big and wellformed. The outside colour is very variable and the flesh of most roots is yellow.
Root crops are mainly grown for carbohydrate production but the other components of dry matter are of course also of some importance. Some data on the composition of dry matter are given in Table 2. The content of crude protein and that of ash was lower in tetraploids than in diploids. The content of nitrogen-free extract (carbohydrate a.o.) was, however, higher. The yield of tops was lower in the tetraploids than in the diploids, e. g., the yield of Sirius was only 86 per cent of that of the diploid strain of Bortfelder.
Seed of tetraploid turnips are larger than seed of diploids, the thousand grain weight is about 3,8 g and 2,4 g, respectively. The yield of seed has not been carefully investigated. At Svalof and the branch stations separate field plots have been grown for seed production of breeding material. As a rule, those with tetraploid turnips have yielded rather well. Three rather large propagation fields with tetraploid turnips (Sirius) have been grown for seed production. Two of them yielded normally, but the third yielded less due to weak and uneven stand and development of the plants. The seed quality of Sirius has been perfect.
There are no definite observations on resistance to club root (Plasmodiopilora brassicae) and to bacterial disease (Pseudomonas erwiniae). It was observed, however, that the tetraploids tend to be a little more resistant to club root but less resistant to bacterial disease than the corresponding diploid material.
The tetraploid Sirius turnip doubtless marks a progress in Swedish root crop breeding. It is more than 10 per cent higher yielding than the best of the diploid strains under the various conditions in different parts of our country. This is an outstanding example of what can be done by the »polyploidy breeding method». The breeding of turnips by chromosome doubling has been intensified and most of the diploid strains and »f'amilies» have been colchicine treated and tetraploid populations established. As many genes and alleles as available may be brought over to the tetraploid populations and the breeding of the tetraploids carried out by the two methods outlined earlier. We want higher dry matter content, especially protein content, and better resistance to disease. The most important goal, of course, is a high and safe yield of dry matter. There seems to be a good possibility of obtaining this by intensive breeding of tetraploid turnips.
A. NYGREN: Pol Y P I 0 ids in Mel and r i u m pro due e d by nit r 0 u s ox ide.
Quite recently, OSTERGREN (1954) has published a paper on the production of polyploids in Crepis capillaris by N.O treatment. During a short visit to   Lund in the spring of 1953 the present author had the privilege of being introduced to the work carried on with nitrous oxide by Dr. OSTERGREN. As a result of this visit an attempt has been made to produce polyploid Melandrium in the same way as OSTERGREN produced polyploid Crepis capillaris, The plants were treated in vessels of two different sizes made by old gas tubes holding about 8 and 36 I, respectively. The tubes were cut of at their upper end, made even and furnished with covers which could be connected to the reduction valve of the nitrous oxide cylinder. The two vessels allowed the treatment of material planted in pots of different sizes. Up to six 15 ern high plants could be treated at the same time in the smaller container, while the big tube took three 50 cm high specimens. Two different species of Melandrium were tested, M. angustiflorum, a hermaphroditic tetraploid, which is related to the Greenlandic M. affine, and the dioecious M. album. As early as 1950 the author had made hybrids between M. angustiflorum and dioecious M. rubrutn. In 1953 nitrous oxide treatment was used in order to produce amphidiploids directly. The dioecious M. album was tested together with its South European ecotype M. divaricatum (=M. macrocarpum) as well as the closely related species. M. Boissieri. The first division in the zygote should be affected by the nitrous oxide. This division occurs in M. album about 12-14 hours after pollination at a temperature of 35 0 C (DEVINE, 1950). As we had no constant rooms at our disposal during the time the experiments were going on, the treatment in each particular case was started between 18 and 24 hours after pollination. Before pollination the plants were kept in a greenhouse with a temperature varying between 20 and 25 0 C.
All attempts to obtain amphidiploids directly between M. angustiflorum and M. rubrum failed in 1953, but on the other hand the experiments with M. album and its allies were successful. All plants belonging to this and related species are dioecious, and crosses were therefore made either between different biotypes of the same species or between biotypes of related species. The nitrous oxide treatment varied between four and 48 hours at pressures between two and ten atmospheres. All plants treated for a longer time than 16 hours set no seeds. The results are to be found in Table 1. It is striking that only three chimaeras have been found in 81 polyploids produced. Only seven of the 78 real polyploids have aneuploid numbers; thus, there are two with 2n=37, two with 2n=47 and three with 2n=50. The results found are condensed in Table 2. It is important to note that treatment in five atmospheres has given not less than 86,1 % polyploids. Thus, there will be no difficulties in the future to produce polyploid Melundrium album with this method. OSTERGREN obtained three triploids of Crepis capillaris in his experiments (1. C., p. 59). In the present case 12 triploids and seven hexaploids were produced. OSTERGREs upposes (p. 61) that the triploids originate according to a particular mechanism causing »multipolar chromosome separation». If the telophase groups of some of these spindles fuse, triploids as well as aneuploids may be formed. The theory gives a very probable explanation of the origin of triploids, and the finding of hexaploids in the experiments with Melandrium album only strengthens its correctness. All hexaploids were obtained in the same experiment during which a pressure of only two atmospheres was used for 16 hours. It is possible that low pressure for a long period has allowed two consecutive divisions of the chromosomes in the zygote to occur without cell-wall formation.