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HARDWICKE'S SCIENCE-GOSSIP. 



BOTANY. 



Evolution in the Vegetable Kingdom. — 

 This is the title of a paper by Lester F. Ward, A.M., 

 of which the second part appears, illustrated by a 

 couple of diagrams, in the "American Naturalist" 

 for August. The writer says that the natural affinities 

 are between apetalous and polypetalous plants, and 

 not between apetalous and gamopetalous, and con- 

 siders that the systematic value of the subdivision of 

 dicotyledons into mono- and di-chlamydeous, and the 

 latter into poly- and gamo-petalous, diminishes with 

 the progress of research. He regards the gamopeta- 

 lous division as the highest in point of structural 

 development, and concludes by saying that " the 

 only one of all the leading forms of [plant ?] life of 

 which we can positively say that it still preserves an 

 upward tendency is the gamopetalous division of the 

 dicotyledons, which, unless arrested by human 

 agency, seems destined to form the dominant type of 

 vegetation for the next geologic epoch." 



Protoplasmic Continuity. — The continuity 

 from cell to cell of the protoplasm of a plant has 

 already engaged the attention of several workers. In 

 the "Botanical Gazette" for August is a translation 

 of a note on the same subject, by M. L. Olivier, 

 presented to the French Academy of Sciences, and 

 published in the "Comptes Rendus." By photo- 

 graphing thin and magnified cross-sections of living 

 tissues, and afterwards examining the negatives with a 

 lens, the cell membranes appear perforated by canals, 

 establishing a communication between the contents of 

 the cells. By projecting the microscope into a dark 

 chamber, so that no light entered his eye, but what 

 came from the instrument, he was enabled to see 

 clearly in more than a dozen plants the interruption 

 of the cell-walls. The method of staining was also 

 resorted to, and by this means if the cell-walls were 

 coloured, colourless spaces were seen, at least in 

 some plants ; while if the protoplasm was stained, 

 the canals traversing the walls are then traceable 

 from their shewing the same colour. This passage of 

 the protoplasm through narrow openings occurs in 

 many cases ; " so that in the tissues of a given plant, 

 where, up to a recent date, we have only observed a 

 multitude of small protoplasmic masses entirely 

 isolated, there is, in reality, a single enormous 

 protoplasmic mass." 



The Absorption of Free Nitrogen by Plants. 

 — It has generally been understood that plants, 

 though surrounded by so large an amount of free 

 nitrogen in the air, are unable to assimilate it while 

 it is in that condition, but are dependent on nitro- 

 genous compounds for their supplies of the element. 

 From some experiments, however, which have been 

 made by Prof. W. O. Atwater, and communicated to 

 the "American Chemical Journal," it appears that 



growing plants can take a large proportion of their 

 nitrogen in the former method. The plan adopted 

 was to grow peas in purified sand, and feed them 

 with solution of nitrates and other compounds, the 

 amount of nitrogen supplied being known. The 

 plants were grown in the open air, but protected 

 from dew and rain, by being taken under cover at 

 night and in rainy weather. Under these circum- 

 stances it was found, by comparing the amount of 

 nitrogen in the seeds and supplied to the soil, with 

 that found in the plants and in the soil at the end of 

 the experiments, that in some cases as much as one- 

 third, or even one-half of the whole nitrogen of the 

 plants had been obtained otherwise than from the 

 soil, that is, it is presumed, in the form of free 

 atmospheric nitrogen. In the other cases, with one 

 striking exception, there was also a gain, though to a 

 less extent, of nitrogen over and above that obtained 

 from the soil. The possibility of the acquisition 

 being from ammonia in the air instead of free 

 nitrogen is noted, but rejected on account of the large 

 amount gained. An abstract of the paper may be 

 found in the " Journal of the Chemical Society " for 

 September, from which this note is taken, and where 

 further details are given. 



GEOLOGY, &c. 



Human Bones. — In some excavations made in 

 January of last year, near the city of Mexico, several 

 human bones were unearthed, an account of which 

 may be seen in the ' ' American Naturalist " for August. 

 The bones exposed comprised part of the cranium, 

 lower and upper maxillce and fragments of collar-bone, 

 vertebrae, ribs and bones from upper and lower limbs. 

 The canine teeth have the peculiarity of being of the 

 same shape as the incisors. No other animal remains 

 were found in a sufficiently satisfactory condition to 

 fix the age of the rock, nor any vestige of ceramic or 

 other modern remains. From considerations pointed 

 out in the paper, however, the writer, Mariano de la 

 Barcena, concludes that the formation in which the 

 bones lay belonged perhaps to the upper Quaternary, 

 or at least to the base of the present geological age. 

 He considers that they belonged to a prehistoric man 

 of ordinary stature and about forty years old. 



Underground Heat. — In a very interesting and 

 suggestive paper in the "Geological Magazine" for 

 September, Mr. J. Starkie Gardner, F.G.S., dis- 

 cusses the question whether the heat which exists 

 below the surface of the earth is likely to be at any 

 time made available for use on the surface. The 

 interior condition of the earth, he says, is still a 

 debated subject ; many geologists believing that it is 

 partially fluid, the fluid which is beneath the solid 

 crust resting also upon a solid interior. If the only 

 reason for the observed prevalence of earthquakes 



