SEVENTEENTH AND EIGHTEENTH CENTURIES 1^9 

 over even the most complicated details in the minute creatures he investi- 

 gated. This he could not possibly have acquired without a high standard 

 of knowledge of the technique of dissection, and, indeed, it was this knowl- 

 edge which excited the admiration of his contemporaries; visitors from far 

 and near were amazed at his fine instruments and the skill with which he 

 handled them — glass tubes drawn out to points as fine as hairs, by means 

 of which organs were spread out and canals injected; scalpules so fine that 

 they had to be ground under a magnifying-glass, and so on. Extraordinary 

 lightness of touch and unique powers of observation enabled him to utilize 

 the methods which he worked out, to which, finally, we must add his love 

 of research, for which he literally gave his life. 



Anato7ny of insects 

 Swammerdam's great work in part contains a collection of anatomical mono- 

 graphs on insects and other invertebrate animals; particularly well known 

 is his exposition of the anatomy of the bee, which even Cuvier considered 

 to be unsurpassed, and further the head-louse, the day-fly, the rhinoceros- 

 beetle, the Helix pomatia, and many more. These monographs, however, 

 are all based on one theory of the evolution of insects and in connexion 

 therewith that of all living creatures. Supported in his investigations by 

 the development of a number of different insects' larv« to pupa and imago 

 and adopting a sharp controversial attitude towards Harvey, Swammerdam 

 declares that the insect does not undergo any transformation, but that merely 

 growth takes place of parts which already existed before. Again and again 

 this statement is emphasized, that no generation, but only an excrescence 

 of parts takes place, wherefore accident plays no part in the evolution of 

 the insect, but what takes place is predetermined. This evolutionary prin- 

 ciple is then applied to the development of the frog from the egg through 

 the various larval stages, and finally, though quite summarily, to the evolu- 

 tion of man, which is likewise made dependent on predetermined necessity. 

 Lastly, the evolution of the bud of plants to leaf and flower is compared 

 in detail with the metamorphosis of insects. In order to facilitate his analysis 

 insects are divided according to their metamorphosis into four groups: 

 (i) those that come from the tgg with all their feet complete — spiders, 

 lice; (i) the animal that has all its feet when it is hatched, but whose 

 wings develop later on — as, for instance, day-flies; (3) those from whose 

 egg comes a larva, either with or without feet, which becomes a pupa after 

 chrysalizing — as, for instance, ants, bees; (4) those in which a larva, like 

 the foregoing, becomes a pupa without chrysalizing — certain flies. In this 

 method of grouping Swammerdam laid the foundations of modern insect- 

 classification, which, as is well known, still rests to a great extent upon 

 the evolutionary history of insects. That he grouped spiders and even snails 

 and worms under his first category is not to be wondered at; all invertebrates 



