THE WONDERS OF LIFE 



particularly large apparatus, these two sciences have 

 long been studied separately, and have been handed over 

 to the medical faculty in the division of the academic 

 curriculum. 



The broad field of morphology may be divided into 

 anatomy and biogeny; the one deals with the fully 

 developed, and the other with the developing, organism. 

 Anatomy, the study of the foniied organism, studies both 

 the external form and the inner structure. We may 

 distinguish as its two branches the science of structures 

 (tectology) and the science of fundamental forms (pro- 

 morphology). Tectology investigates the features of the 

 structure in the organic individual, and the composition 

 of the body out of various parts (cells, tissues, and 

 organs) . Promorphology describes the real form of these 

 individual parts and of the whole body, and endeavors 

 to reduce them mathematically to certain fundamental 

 forms (chapter viii.). Biogeny, or the science of the 

 evolution of organisms, is also divided into two parts — 

 the science of the individual (ontogeny) and of the stem 

 or species (phylogeny) ; each follows its own peculiar 

 methods and aims, but they are most intimately con- 

 nected by the biogenetic law. Ontogeny deals with the 

 development of the individual organism from the begin- 

 ning of its existence to death; as embryology it ob- 

 serves the growth of the individual within the foetal 

 membranes; and as metamorphology (or the science of 

 metamorphoses) it follows the subsequent changes in post- 

 foetal life (chapter xvi.). The task of phylogeny is to 

 trace the evolution of the organic stem or species — that is 

 to say, of the chief divisions in the animal and plant 

 worlds, which we describe as classes, orders, etc. ; in other 

 words, it traces the genealogy of species. It relies on the 

 facts of paleontology, and fills up the gaps in this by 

 comparative anatomy and ontogeny. 



The science of the vital phenomena, which we call 



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