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SCIENCE. 



length of the day was increasing — getting gradually 

 longer and longer. But how long has this been going 

 on ? Yesterday was shorter than to-day. The d-ay 

 which Homer had was shorter than our day, but not 

 indeed to any appreciable extent. There can be no 

 doubt, however, that a million years ago the day was 

 appreciably shorter than the day is at present. He wished 

 to conduct them back to an exceedingly remote period, 

 to a critical epoch in the history of the earth. That epoch 

 must have been more than fifty millions of years ago, 

 but how much more he could not tell. At that extremely 

 remote time the day was greatly less than it is at pres- 

 ent. It was only, indeed, a fraction of its present amount, 

 being only from two to four hours long. He would trace 

 back the moon to the same remote epoch to which he 

 had conducted the earth. The tides in the earth are 

 forcing the moon gradually away from us at present. 

 The moon was therefore formerly nearer to us than it is 

 now. Millions of years ago the orbit of the moon was 

 much less than it is at present. The time of the moon's 

 revolution was much smaller and the moon must have 

 been quite close to the earth, and whirled round the lat- 

 ter in a period of from two to four hours equal to the 

 period of the earth's revolution on its axis. Such, then, 

 is the primeval condition of things to which the tracing 

 of tidal evolution conducted. Antecedent to this critical 

 epoch they could hardly go with any degree of certainty. 

 After explaining Darwin's theory in reference as to the 

 supposed rupture of the earth at a very remote period of 

 time, and the consequent formation, of the moon, the 

 lecturer proceeded to speak of the surprise with which 

 astronomers realized that the small interior satellite of 

 Mars revolved on its axis in less than a third of the time 

 — nearly 24 hours — which the primary occupied in re- 

 volving on its own axis. He also spoke of the tremen- 

 dous forces in action at remote periods when tides rose 

 to a height of a thousand or two thousand feet, scouring 

 rocks and carrying enormous quantities of matter to the 

 sea, and when that action caused so much comparatively 

 rapid manufacture of strata. 



MR. DARWIN ON DR. HAHN'S DISCOVERY OF 

 FOSSIL ORGANISMS IN METEORITES. 



Dr. Hahn's discovery, of which an elaborate account 

 was given in No. 50 of Science, has stirred up a lively 

 discussion of this highly interesting subject. Dr. Hahn 

 has taken steps to enable Prof, von Ouenstedt, the re- 

 nowned Tubingen geologist, and all others who ex- 

 pressed the desire to examine his microscopic preparations. 

 It is understood that all those who have availed themselves 

 of the opportunity thus offered have become convinced of 

 the genuineness of Dr. Hahn's discovery. 



It is very interesting to note the position taken by the 

 greatest of living evolutionists in this controversy, if it 

 can still be called such. Charles Darwin, on receipt of 

 Dr. Hahn's work, wrote to him : 



"... It seems to be very difficult to doubt that your 

 photographs exhibit organic structure . . .," and further- 

 more : 



"... your discovery is certainly one of the most im- 

 portant." 



Not content with the mere presentation of h ; s work, 

 Dr. Hahn visited the veteran zoologist and brought his 

 preparations to him for inspection. 



No sooner had Mr. Darwin peered through the micro- 

 scope on one of the finest specimens when he started up 

 from his seat and exclaimed : 



'• Almighty God ! what a wonderful discovery ! Won- 

 derful !" 



And after a pause of silent reflection he added: 

 " Now reaches life down !" 



The latter remark no doubt refers to the proof fur- 

 nished by Dr. Hahn's discovery that organisms cm reach 



our planet from celestial space. It is an acknowledgment 

 of the relief Mr. Darwin must have felt in not being 

 forced to a belief in a primeval " generatio equivoca." 



As was suggested in the paper referred to, "the 

 Richter-Thomson hypothesis of the origin of life on the 

 earth has become a tangible reality !" R. 



AN AFTERNOON ON PASSAIC RIVER. 



On the 25th day of last month the editor, in company 

 with his former colleague on the Quarterly, Mr. J. L. 

 Wall, escaped from the city and made a trip to the town 

 of Belleville, on the Passaic River. A row-boat was 

 engaged, and we proceeded to collect specimens from 

 along the shores. Not many species of algas were found, 

 nor was there any great variety of animal forms, but the 

 wa f er-plants, so hardy and useful in aquaria, the Anacha- 

 ris Canadensis and Vallisneria spiralis, were abundant. 

 Reaching over into the shallow water, it was an easy 

 matter to obtain perfect plants of Vallisneria with good 

 roots, and we collected a number of them. The Ana- 

 char is grows so readily without roots that the more fresh 

 looking stems were carried home without regard to the 

 roots. An old can was made use of to carry home some 

 of the river mud, in which to plant the Vallisneria. 

 The mud was placed in the bottom of a tall specie jar, the 

 roots of the plant were properly embedded, and the jar 

 filled with water. The next morning, after the water was 

 cleared by settling, the mud was covered with a layer of 

 clean sand, which tends to prevent riling of the water by 

 a slight disturbance. All the leaves of the Vallisneria 

 were removed, so that a new growth might start in the 

 aquarium. It is probable that we will thus obtain some 

 vigorous plants of Vallisneria for use during the coming 

 winter. The Anackaris was simply thrown into a large 

 aquarium, where it will doubtless grow without further 

 care. Rowing about slowly, a long, green, spiral filament 

 was observed reaching up to the surface of the water. 

 It was two or three feet in length, and bore a peculiar 

 flower at the end. This was the female flower of Vallis- 

 neria, a very interesting object for study ; it was quite a 

 surprise to us, as the plam does not usually flower as 

 early as July. Looking toward the shore, the water was 

 covered with an innumerable quantity of white specs, 

 which attracted our curiosity. Rowing up to them, we 

 found that they were the male flowers of Anackaris. 

 These are very curious flowers. The long, tubular peri- 

 anth, sometimes two or three inches in length, reaches 

 from the axil of a leaf to the surface of the water, and 

 bears the stamens above. It would easily be mistaken 

 for the flower-stem, but it is really the tubular perianth. 

 These flowers were very abundant, so that the water 

 appeared white with them. The pollen-grains were 

 numerous, and could be seen floating about on the water 

 in little clusters resembling snow-flakes. Potamogeton 

 was abundant, in several forms, and the common arrow- 

 plant, so named from the shape of the leaf, Pontedaria 

 cordata, which is also good for large aquaria. This plant 

 should be set in a flower-pot, with suitable soil in which 

 to root, and then submerged, either wholly or in part. 



Among the algae, two species of Oscillaricaceas were 

 found quite actively moving Oscillaria tenius and littor- 

 alis, and Lyngbya majuscula. The most interesting 

 specimen of all, however, was a species of Ulothrix, a 

 very common, filamentous, green alga?, in which the cells 

 are about as long as they are wide. It was interesting 

 because when we examined it, at about seven o'clock the 

 next morning, the process of giving off swarm-spores had 

 just begun. The entire contents of each cell in whole 

 filaments, quickly formed into green, spherical masses, 

 which began to move about in the confined space within 

 the cells ; soon the cell-walls ruptured, and the contents 

 escaped as very active swarm-spores, somewhat elon- 

 gated in form, and furnished with four long, whip-like 

 appendages, or llagella, by means of which they could 



