226 FATHERLESS PROGENY 



polyps, which fix themselves to rocks or weeds, and grow 

 up to bud and multiply by fission, and eventually to pro- 

 duce again by fission a generation of jelly-fishes ! Such a 

 marvellous history of alternating modes of reproduction has 

 been discovered, and described in greatest microscopic detail 

 and with most ample pictorial representations of all the 

 minutest structures of the organisms studied, not only in 

 many marine polyps, but also in the case of many para- 

 sitic worms, such as the tape-worms and the liver-flukes. 

 Some of the most fascinating cases, on account of the 

 beauty of the little creatures concerned, are found amongst 

 the surface-swimming Ascidians of the sea the glass-like 

 Salps (see p. 303). But our common ferns and mosses also 

 show this same alternation of sexual and sexless genera- 

 tions, the two generations differing greatly in size, form, 

 and structure from one another, whilst the whole history 

 of "flowers" and their structure is bound up with a wonder- 

 ful " telescoping " or rolling of the two generations (sexless 

 and sexual) into one plant ! (See Chapters VII and VIII.) 

 It was not until long after Harvey's time that these 

 things were understood, and there was every excuse in 

 the absence of observation of the facts, especially those 

 yet to be revealed by the microscope for the erroneous 

 suppositions and explanations which were formerly enter- 

 tained as to the mode of reproduction of the less familiar 

 plants and animals. If we go back to the starting-point 

 of European science, to the great Aristotle, we find that 

 he had formed singularly correct conclusions as to the 

 reproduction of the larger kinds of animals, though he 

 knew nothing about " sperms," having no microscope, and 

 only legarded the fluid produced by male animals as 

 exercising a fertilising effect on the eggs, which in many 

 instances are large enough for anyone to see. But, of 

 course, he could not have any knowledge of the egg-cell, 

 nor does he say anything about the reproduction of 



