SCIENCE- GOSSIP. 



357 



occasionally being considerable, and at other times 

 less so. 



During the late spring of 1898 I prepared about 

 eight cultures of pollen, in water and in sugar- 

 and-water, with the result that no examples of 

 emission of pollen-tubes were noticed. Strangely 

 enough, not even in the case of pollen selected 

 from plants bearing fruit was germination ob- 

 served. This negative evidence did not, however, 

 lead me to assume that seed is produced partheno- 

 genetically without the influence of the male 

 element. The following spring gave very satis- 

 factory results as to the capability of the pollen to 

 germinate. Usually the grains germinated more 

 readily in the water cultures than in the sugar- 

 and-water preparations. In the case of pollen 

 taken from a cultivated plant, which the previous 

 year was found bearing fruit at Shenley, more 

 germinating grains were observed in the sugar- 

 and-water preparations than in the water cultures. 

 The observations of 1899 were made on pollen 

 obtained from plants flowering from March to 

 June, and some of the pollen was obtained from 

 plants bearing fruit. Apart from germination, 

 the chief noticeable feature of most cultures of 

 pollen was that the proportion of imperfect 

 pollen-grains was much smaller than in the 

 pollen-cultures of the previous year ; in fact, the 

 shrivelled pollen -grains were scarcely present. 

 An exception was in the case of pollen taken from 

 plants growing in a damp situation by a stream 

 near Theydon Bois in Essex. The proportion of 

 imperfect grains was there as much as about six to 

 every eight regularly formed grains. Continued 

 observations during the spring of 1900 were as 

 successful as those of the previous year. In one 

 instance only did the grains fail to germinate, and 

 in these preparations most of the pollen-grains 

 absorbed water to such an extent as to burst the 

 membranes. 



In all preparations of pollen, it is but a minority 

 of the grains which emit pollen-tubes. Some of 

 the pollen-tubes reach a great length in comparison 

 with the size of the grains, being twenty or more 

 times as long as the diameter of the grains from 

 which they originate. A portion only germinate, 

 and I think these alone possess the power of 

 emitting pollen-tubes. It is well, however, to 

 retain in view that the conditions presented by 

 water and sugar-and-water cultures are vastly 

 1 1 i ITVrent f rom those occurring in nature. It may 

 perhaps not be out of place to mention here that 

 seed of the lesser celandine procured at Shenley 

 and in Surrey germinated readily in the year 

 following gathering. 



The imperfect character of these observations 

 upon R. ficaria is very apparent, and from them 

 it would be extremely unwise to draw con- 

 clusions as to the general behaviour of the species. 

 Further, the results of observations, however ex- 

 tensive, of one observer only can never be taken as 



characteristic of the species under investigation. 

 To achieve this end ii. is necessary that observa- 

 tions of many investigators should be pieced 

 together into one continuous whole. Personally, 

 I entertain the opinion that fruit of the lesser 

 celandine, if not generally produced, is by no 

 means rare, and can, when looked for, usually be 

 found. To the habit of the plant is due the fact 

 that fruit, even when produced, is apparently 

 absent. Usually after flowering, the peduncle of 

 a plant is strengthened in order to support the 

 maturing fruit. This is not so in Ii. ficaria, 

 in which species the fruit-stalks are flaccid and 

 lie low among the leaves. Occasionally, the 

 stalks become curved as much as is the habit 

 among the water crowfoots, and the. heads of 

 achenes seem almost to burrow into the soil. This 

 depressed habit of the fruit-bearing stalks, together 

 with the large achenes and the formation of tubers, 

 are probably the causes of the plants being 

 gregarious. 



That there is an undoubted connection between 

 the formation of tubers by which asexual repro- 

 duction is effected and the production of seed is 

 evident. Usually in seed-bearing plants of the 

 lesser celandine the production of tubers is not 

 marked on the parts above the soil. ' That a 

 plentiful formation of axillary tubers, is preju- 

 dicial to the production of seed is suggested 

 by the circumstance that in one locality near 

 South Mimms, in 1898, where the plants were 

 abundantly producing axillary tubers, one or 

 several together, only two plants could be found 

 bearing seed, and this so small in quantity that it 

 was limited to two stalks, each with five well 

 grown carpels among the undeveloped ovaries. 

 If, as is likely to be the case, the two methods of 

 reproduction cannot very well exist side by side, 

 it may be that, in localities where the chief mode 

 of propagation is by means of tubers, there is this 

 inability, not from any defect in the sexual consti- 

 tution, but by reason of the plastic food materials 

 being diverted from the perhaps fertilised ovaries 

 towards the tubers. It may be thought that 

 dryness of situation, in a measure, affects seed- 

 production, though my observations do not lead to 

 such a conclusion. It is true fruiting plants have 

 been met with in dry situations ; but, on the 

 other hand, such plants have been found in 

 damp places, such as at the base of hedge-ban k> 

 and by ditches. In 1898 a locality where fruit 

 was produced abundantly was in a wet, clayey 

 field; and the instance mentioned of tuber-forma- 

 tion near South Mimms occurred on a very dry, 

 sandy bank. Especially wet situations, as by 

 watercourses and streams, may favour tuber forma- 

 tion, to the detriment of the sexuality of tin- 

 plants, for in such places the chances of the 

 flowers perfecting seed may be considerably 

 lessened. It may have been due to the influence 

 of the surroundings that failure attended my 



