126 



by the State Seed-Testing Station for crop seed, and germination results 

 obtained upon an unheated apparatus placed in an open verandah, shows 

 that all the species tested, with a single exception, germinate most rapidly 

 and best under the circumstances last mentioned. O. Rostrup suggests 

 that when Nobbe and Haenlein, in examinations similar to those men- 

 tioned, found very low germination results, it is probably due to the fact 

 that they used too high a temperature (see " Die landwirtschaftlichen 

 Versuchs-Stationen," vol. xx., p. 74, and vol. xxv., p. 465, BerUn). 



In the case of a small number of the species in question several samples 

 were tested. The progress of germination of the various samples of the same 

 species was not in all oases aUke. Probably the germination is influenced 

 by the crop, degree of maturity, provenance, and, perhaps, the strain or 

 racial characteristics. In future examinations of this kind it would be- 

 desirable to use samples harvested from single plants. Even with this 

 precaution as to the material losed for the test, it is impossible always to 

 be sure that the seed germinates equally. Professor Correns has thus 

 pointed out that, among other things, the germination is, in some cases,, 

 influenced by the position of the seed in the fruit or in the inflorescence; 

 the seeds from the ray florets of many of the compositae have proved thus 

 to germinate otherwise than seeds from the disc florets {see " Jahresbericht 

 der Vereinigung fiir angewandte Botanik," 8th annual publication, 

 1910, p. 258). 



III. — The influence of the degree of maturity on the germinating capacity of 

 weed seeds and the permanence of the germinating capacity. 



In order to throw light upon this matter, the writer has carried out 

 the investigations mentioned below. In 1904 " ripe " as well as " unripe " 

 seeds of the species stated in Table 1 {see p. 133) were collected. The 

 unripe seeds were still greenish, had a tough albumen, and were so firmly 

 attached to the mother -plant that they had to be picked off. The ripe 

 seeds were by a slight touch easily removed from the plant, and the seed- 

 shell or seed-vessel had the appearance typical of maturity. Ripe and 

 unripe speeds were harvested from the same piece of ground, but not abso- 

 lutely from the same plant. The seeds were stored in paper bags in drawers 

 situated in rooms which were heated during the winter, so that the 

 moisture content, being greatest in the unripe seeds at the time of harvest, 

 became comparatively rapidly almost alike in ripe and unripe seeds. 

 Shortly after the harvesting and each following autumn, 100 ripe and 

 unripe seeds respectively of each species were placed to germinate upon a 

 Jacobsen tank in an open verandah, as described on p. 125. Table 1 shows 

 the main results of these examinations. 



Under, the conditions given, the ripe seeds retained their germinating 

 capacity for the longer time; the unripe seeds of most of the species 

 germinated more rapidly than did the mattire, especially in the first years 

 after the harvesting of the seed. 



In Table 2 (see p. 134) an account is given of how several other species 

 have retained their germinating power during a series of years. The con- 

 ditions of storing and the method of germination have been the same as 

 indicated above (dry storing and germination on unheated apparatus). 



IV. — How many weed seeds are found in the soil ? 



(Some information as to the number of seeds which variolas weed plants 

 are able to give is stated hereunder.) 



The seeds of some plants of various indigenoios species were occasionally 

 coTinted (" Tidsskrift for Landbrugets Planteavl," vol. 13, pp. 35-37). Of 

 the results, mention should be made of the following :— 



Daucus carota. — ^A plant standing isolated gave 110,000 seeds, while 

 seven plants in a grass field gave on an average about 4,000 seeds per plant. 



Plantago lanceolata. — ^A vigorous plant in a grass field gave about 

 15,000 seeds; six smaller specimens in the same field gave on an average- 

 about 2,500 seeds. 



