Cell and Protoplasm. 101 



Chapter IX. < 

 Cell and Protoplasm. 



The Early MicroscopislxBichafs Step The Cell-theory Corroboration 

 of the Celt-theory Criticism of the Cell-theory Modern Analysis 

 of the Cell Cell -division The Cell-cycle Structure of the Cell- 

 substance Protoplasm Anabolism and Katabolism Conception of 

 Ultimate Vital Organization. 



Harvey made his minuter observations with the aid 

 of a simple lens such as every field-botanist now carries 

 in his pocket, and one must admit that with- The Early 

 out some better instrument the analysis of Microsco- 

 structure could not have advanced far be- plsts> 

 yond what Harvey achieved. The better instrument, 

 which opened up a new world, was the compound 

 microscope, invented about 1600 by Hans and Zacharias 

 Jansen, and rapidly improved by other workers. In the 

 seventeenth century it was used to good purpose by a 

 number of enthusiastic observers who revealed minutiae 

 of structure hitherto unsuspected. Malpighi in Italy, 

 Leeuwenhoek and Swammerdam in Holland, Hook and 

 Grew in England, were among the most notable of these 

 early histologists. 



When we consult the works of the early microsco- 

 pists we cannot help feeling that they often played with 

 their new scientific toy, just as we often play Bichat's 

 with stains and microtomes. They magni- ste P- 

 fied without purpose, and accumulated descriptions and 

 figures of what are called "interesting objects" or 

 "microscopic curiosities". The play-period in science 

 as well as in life may be essential as an apprenticeship 

 to serious work; but it must be allowed that there is no 

 direct gain in magnifying an object a thousand times, 

 or staining it with three colours, unless the magnifying 

 and the staining help us to understand the object better, 

 or keep us from misunderstanding it. 



Without any depreciation of the keen vision of Leeu- 

 wenhoek or Swammerdam and their contemporaries, 



