388 ANNUAL OF SCIENTIFIC DISCOVERY. 



besides one hundred and fifty unbound volumes and pamphlets, and these 

 latter are not the least valuable portion of the library, consisting as they do 

 of important monographs, a form in which much that has been done in 

 Algology and Microscopy is as yet only to be found. Among the works 

 are the splendid Microgcologie of Ehrenberg, the works of Kutzing, Queck- 

 ett, Ralfs, Hassall, Smith, Agardh, Harvey, Lindley, and Hutton. Indeed, 

 nearly everything of importance relating to microscopic science is here. In 

 addition to the books, there are nearly three thousand sketches or drawings 

 of microscopical objects, all carefully arranged and catalogued. 



PRODUCTION OF SEXES AT WILL. 



Many curious investigations have been instigated in regard to this point 

 in the world of nature. It is a matter of familiar knowledge that the male 

 and female characteristics of the higher species of the animal creation, are 

 not produced in the same individual as they are in the great majority of the 

 higher species of plants. The organs, as will be seen, from which the two 

 are evolved, are, however, so nearly related to each other in intimate nature, 

 that the one may be readily mistaken for the other in the earliest period of 

 their formation. Physiologists now incline to the opinion that the fertilizing 

 vesicle is merely a germ vesicle, in a somewhat more exalted state of devel- 

 opment. Mr. Knight has shown that plants, like the oak, that bear the male 

 and female flowers on separate individuals, may be made to produce either 

 at will, by regulating the supply of light and heat according to the end in 

 view. If the heat be excessive as compared with the light, male flowers 

 only appear ; but if the light be in excess, female flowers are produced. He 

 also found that whenever the eggs of birds are not allowed to be fertilized 

 until immediately before they arc laid, and therefore their own intrinsic de- 

 velopment has been carried to the highest possible pitch before renewed vivi- 

 fication of the germ vesicle is effected, as many as six out of every seven 

 of the birds subsequently hatched proved to be males. * * * Quetelet 

 believes that the relative ages of the male and female parent, influence the 

 sex of the offspring produced, to a very considerable extent. In support of 

 this theory M. Hofacker has shown that when the father is considerably 

 younger than the mother, the proportion of female to male children is gener- 

 ally as ten to nine ; but that when, on the contrary, the father is nine years 

 older than the mother, the proportion of male offspring to female is as five 

 to four, and when eighteen years older, as two to one. In a general way, 

 more males of the human species are born into the world than females. If 

 all Europe be included in the estimate, the proportion of male to female births 

 is about 106 to 100. Possibly, if Quetelet's views be based on truth, this 

 preponderance on the side of males may be due to the fact that in civilized 

 communities men, from prudential and other motives, mostly marry women 

 younger than themselves. But there are other reasons why this preponder- 

 ance exists. Three male children are born dead to every two female. 

 Gardner on Sterility. 



