viii PREFACE 



the development of Hydra and to the so-called sexual pro- 

 cess in Penicillium, and described Nitella instead of Chara, 

 and Polygordius instead of the earthworm. The last-named 

 substitution is of course only made possible by the book 

 being intended for the study and not for the laboratory, but 

 I feel convinced that the student who masters the structure 

 of Polygordius, even from figures and descriptions alone, 

 will be in a far better position to profit by a practical study 

 of one of the higher worms. 



Lessons XXVII. and XXX. are mere summaries, and can 

 only be read profitably by those who have studied the 

 organisms described, or allied forms, in some detail. Such 

 abstracts were however necessary to the plan of the book, in 

 order to show how all the higher animals and plants may be 

 described, so to speak, in terms of Polygordius and of the fern. 



For many years I have been convinced of the urgent need 

 for a simplification of nomenclature in biology, and have now 

 attempted to carry out a consistent scheme, as will be seen 

 by referring to the definitions in the glossary. Many of 

 Mr. Harvey Gibson's suggestions are adopted and three new 

 words are introduced phyllula, gamobium, and agamo- 

 bium. I expect and perhaps deserve to be criticised, or, 

 what is worse, let alone, for the somewhat extreme step of 

 using the word ovary in its zoological sense throughout the 

 vegetable kingdom ; and for describing as the venter of the 

 pistil the so-called ovary of Angiosperms. I would only 

 beg my critics before finally pronouncing judgment to try 

 and look at the book, from the point of view of the begin- 



