532 



SCIENCE. 



'■[Vol. IV., No. 97. 



Krebs, by the use of a more powerful and a lighter 

 motor and a long balloon, reached a speed of about 

 5.5 metres a second in their first two experiments, 

 and 6.5 metres a second in their recent experiments 

 of Nov. 8, 1884, or 23.5 kilometres an hour, with a 

 five-horse power, and fifty revolutions of the screw a 

 minute. 



On the 9th of November, says Tissandier, the wind 

 was moving at the rate of 8 kilometres an hour. 

 When the balloon was going with the wind, its speed 

 was equal to 23.5 plus 8 kilometres, or 31 kilometres, 

 an hour: on the other hand, when it went against the 

 wind, its speed was 23.5 kilometres minus 8 kilome- 

 tres, or 15.5 kilometres, an hour. The balloon was 

 easily guided in all directions. 



was easily effected, as before. The accompanying 

 maps give the exact routes of the two trips. 



These new experiments are decisive. Navigation 

 of the air by means of long balloons provided with 

 screws is demonstrated. We will repeat, what we 

 have already said many times, that to be practicable 

 and useful, aerial ships must be made very long, of 

 very large dimensions, which shall carry very large 

 machines, capable of giving a speed of from 12 to 15 

 metres a second, allowing their working at almost 

 any time. When the wind is high, or there is a squall 

 or tempest, aerial ships must remain in port, as other 

 vessels do. It becomes now only a question of 

 capital. 



The first ascent took place at noon. When the 

 balloon had risen above the surrounding obstruc- 

 tions, the working of the screw was begun ; and the 

 balloon, tacking about, was directed in a straight line 

 toward the viaduct of Meudon, which it soon reached. 

 It crossed the Seine below the bridge of Billancourt, 

 became entangled on the right bank of the river, and 

 the motor was stopped, and the balloon allowed to go 

 with the wind, in order to measure the rate of the 

 current. After a rest of five minutes, the machine 

 was again put in motion; and the balloon, guided by 

 the rudder, described a semicircle of about 160 metres 

 diameter, and returned to its starting-point at a slow 

 rate, but with perfect stability. At three p.m. Kenard 

 and Krebs began a second experiment. The balloon 

 arose a second time, and made several excursions in 

 the neighborhood of Chalais ; but the fog was so 

 thick, that the second ascent only occupied thirty- 

 three minutes through fear of losing sight of the 

 landing-place. A return to the place of departure 



have not been able to provide a shelter for the inflated balloon, 

 that it might be ready to set out in favorable weather. 



A NEW LAW OF ORGANIC EVOLUTION. 



I have in another place given many reasons for 

 believing that the male cell has, by division of labor, 

 gradually acquired the function of exciting variation, 

 while the ovum transmits the established character- 

 istics of the race. The following facts, among others, 

 seem to indicate that a specialization of this sort actu- 

 ally exists. 1.° There is no evidence that the func- 

 tions of the two sexual elements are alike, but the 

 possibility of parthenogenesis shows that the ovum 

 in itself can transmit all the established character- 

 istics of the race. 2°. Organisms born from fertilized 

 eggs or seeds are much more variable than those which 

 are produced asexually. 3°. The children born from 

 a male hybrid with the female of either pure form are 

 much more variable than those from a female hybrid 

 with the male of either pure form. 4°. Parts which 

 are confined to males, or which are of more functional 

 importance in males than in females, are much more 

 variable than parts which are confined to females, or 

 which are of more functional importance in females 

 than in males. 5°. Males are more variable than 

 females. 6°. The male leads, and the female follows, 

 in the evolution of new features, as is shown by the 

 fact that the females of allied species are more like 

 each other, and more like the young, than the males 

 are. This cannot be due to sexual selection ; for it 

 holds true to a remarkable degree in domesticated 

 pigeons, and in other animals which are paired by 

 the breeder. 



Now, if it is true that the tendency to vary comes 

 through the influence of the male parent, it will be 

 for the advantage of the species to give birth to an 

 excess of females, so long as the conditions of life 

 are favorable, and change is not needed, and to give 

 birth to an excess of males whenever the conditions 

 of life become unfavorable, and thus demand new 

 modifications. 



Diising has recently published 1 a very valuable and 

 highly suggestive series of papers upon the laws which 

 regulate the sex of the embryo in mankind, and in 

 other animals, and in plants; and the facts which he 

 has brought together seem to show that this specializa- 

 tion actually exists, and that a favorable environment 



Jenaische zeitschrift, xvi. iii. 1883, 428, and xvii. 1884, 592- 



940. 



