iio THE HISTORY OF BIOLOGY 



The icthyology of Artedi 

 His work was published by Linnasus with the assistance of a Dutch patron. 

 It was probably in all essentials the work of Artedi, though Linnasus made 

 some additions here and there. The work purports to be a complete mono- 

 graph on fishes; the anatomical section, however, is of minor importance. 

 The chief interest lies in the presentation of the theory of the system, which 

 is incorporated in the part entitled " Philosophia ktbyologka.'' In this are 

 discussed with sharp criticism the various systematical categories. He starts, 

 after the model of Tournefort, with the genus, which is defined as a collec- 

 tion of species that, as regards the shape, position, number, and mutual 

 relation of the parts, agree with one another and differ from other genera. 

 The species, moreover, he bases, not like Ray and Linnasus on common ori- 

 gin, but on dissimilarity in the same genus in respect of some individual 

 part of the body, a principle the weakness of which in comparison with 

 Linnicus's becomes at once apparent. As higher categories he adduces classes 

 and orders; the classes should be "natural" — that is, be based upon agree- 

 ment in several essential parts and not upon unessential factors, such as oc- 

 currence, size, and the like. Fishes form one such "natural" class, owing 

 to the shape of their body and their fins, whales nevertheless still being 

 counted in the "natural" class. The orders into which the class is divided 

 are on the whole the same as those still in use today — a proof of Artedi 's 

 systematical acumen; selachians, acanthopterygian and malacopterygian 

 osseans are categories invented by him. Linnasus adopted his icthyological 

 system unaltered in his Systema natura. 



Linnaus's first great work: Systema naturae 

 This great work of Linnasus, the natural system "in which nature's three 

 kingdoms are presented divided into classes, orders, genera, and species," 

 was published, as already mentioned, in Leyden in 1735. At the same time 

 was printed the above referred to Fundamenta botanka, and three years later 

 the important work Classes flantarum. These three really contain all that 

 is essential in the reform of classification which Linnasus carried out. Like 

 Ray, but in contrast to Tournefort, Linnasus as a systematician takes as his 

 starting-point the idea of species. He adopts Ray's theory of the species as 

 created from the very beginning and immutable, laying this down as a fun- 

 damental principle without limitations or exceptions. "We count as many 

 species as have been created from the beginning; the individual creatures 

 are reproduced from eggs, and each egg produces a progeny in all respects 

 like the parents." Thus there is no room for spontaneous generation, no 

 possibility for the seeds of one plant to give rise to a plant of a different 

 kind. Rather it was expressly maintained that in the beginning there was 

 created of each species one single pair, one of each sex, so that all individuals 

 of the same species possess a common origin. Again, there exist as many 



