NOTES ON RECENT RESEARCH. 



265 



Not only was light growth stimulated in the manner shown by the 

 chart, but a marked tendency to run to seed became noticeable in all 

 plants near the light. 



Sugar Beets show interesting results. It has been well known that 

 in the United States Sugar Beet grows much more profitably in high 

 latitudes, where short growing seasons are the rule, and where the sun 

 shines with great intensity for days uninterrupted by cloud or fog. The 

 result of the experiments showed that while the size and weight of the 

 roots under the gaslight were less than under normal conditions, the 

 foliage was greater under the gaslight. But when analyses for sugar 

 were made the percentages were greater for the roots under the light in 

 the proportion of 6*10 to 5*53. 



The author adds an interesting section upon the range of the influence 

 of the incandescent gaslight and of the arc light. It was noticeable in 

 his experiments that the maximum of influence was not upon the plants 

 growing nearest to the light, but at a short distance from it. This 

 is explained by the way the light is distributed from the glowing 

 mantle, for the angle covered by the gas lamp is not only much greater 

 than for the electric light, but the distribution of the light from the latter 

 is more localised, and is more intense than is the case with the Welsbach. 

 The greatest quantity of light is given off from the electric light within 

 the area 1H to 24 feet from the perpendicular ; while the light is much 

 less intense from the Welsbach, and is given off over a belt covered by 

 8^ to 17 feet from the perpendicular (i.e. through the light itself), 12 feet 

 being the place of maximum intensity of the light. 



The range of the Welsbach lamp is from 12 to 16 feet for the greatest 

 stimulating influence, with a marked influence up to 24 feet. — 67. H. 



Structure &c. of Pollen. 

 Pollen-tube, Development of, and Division of the Generative 

 Nucleus in certain Species of Pinus. By Miss Margaret C. Fergusson 

 [Ann. Bot. vol. xv., No. lviii., p. 193). — This is a valuable study by the 

 authoress, and incidentally an important resume of the work done by 

 others in a field of investigation which has waited, to a large extent, for 

 modern means of research, and in which, at least for other genera, much, 

 no doubt, remains to be done. Three plates with fifty-one figures are 

 given and some sixty-one papers are cited. Among the facts stated in 

 the summary are the following : The structure of the pollen-grain agrees 

 fully with that given by Strassburger, 1892. The pollen-grain germinates 

 very soon after pollination, and the vegetative nucleus immediately passes 

 into the tube. During the first season the pollen-tube grows very slowly, 

 and it may be broad and irregular in outline or it may branch freely. 

 Shortly before fertilisation the generative cell, followed by the stalk cell, 

 moves into the pollen-tube. The generative cell, as the other cells of the 

 pollen-grain, is never limited by a well-defined cell-wall, and consists at 

 the time of its division of an irregular protoplasmic body, in the upper 

 part of which the nucleus lies. In the division of the generative nucleus 

 the spindle is extra-nuclear and unipolar in origin. The nuclear mem- 

 brane persists along the upper part of the nucleus until the early stages 

 in the formation of the daughter-nuclei. This division takes place a little 



