THE WONDERS OF LIFE 



ticularly the case in many of the platodes (trematodes) 

 and articulates (crustacea and insects). In the bees we 

 have the remarkable feature that it is only decided at 

 the moment of laying the egg whether it is to be fertil- 

 ized or not ; in the one event a female and in the other a 

 male bee is formed from it. When Siebold proved at 

 Munich tiiese facts of miraculous conception in various 

 insects, he was visited by the Catholic archbishop of the 

 city, who expressed his gratification that there was now 

 a scientific explanation possible of the conception of the 

 Virgin Mary. Siebold had, unfortunately, to point out 

 to him that the inference from the parthenogenesis of 

 the articulate to that of the vertebrate was not valid, 

 and that all mammals, like all other vertebrates, repro- 

 duce exclusively from impregnated ova. We also find 

 parthenogenesis among the metaphyta, as in the chara 

 crinita among the algae, the antennaria alpina and the 

 alchemilla vulgaris among the flowering plants. We are, 

 as yet, ignorant for the most part of the causes of this 

 lapse of fertilization. Some light has been thrown on 

 it, however, by recent chemical experiments (the effect 

 of sugar and other water-absorbing solutions), in which 

 we have succeeded in parthenogenetically developing 

 unfertilized ova. 



In the higher animals the complete maturity and 

 development of the specific form are requisite for repro- 

 duction, but in many of the lower animals it has been 

 observed recently that ovula and sperm-cells are even 

 formed by the younger specimens in the larva stage. If 

 impregnation takes place under these conditions, larvae 

 of the same form are bom. And when these larvae have 

 afterwards reached maturity and reproduced in this 

 form, we call the process dissogony ("double-genera- 

 tion"). It is found in many of the cnidaria, especially 

 the medusae. But if larvae propagate by unfertilized ova, 

 and so reproduce their kind parthenogenetically, the 



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