52 THE CELL DOCTRINE. 



eminently the subject of changes, the seat in which 

 changes take place. And herein, we believe Huxley 

 to have been misinterpreted by some who have 

 presented his view r s elsewhere, as Dr. Beale,* who 

 represents him as believing the periplast active, that 

 it is the efficient agent, that it sends in partitions, 

 &c. But that Prof. Huxley considered it passive we 

 believe may be legitimately inferred from his text. 

 As the seat of change, however, accomplished not as 

 "the result of any metabolic action of the endoplast, 

 but of intimate molecular changes in its substance, 

 which take place under the guidance of the vis es- 

 sentialis," the periplast is differentiated into every 

 variety of tissue. Finally, we have the distinct ad- 

 mission, as seen in the sentence last quoted, and also 

 throughout the entire expression of the theory, of a 

 controlling, guiding principle, through which the 

 differentiation is accomplished. This principle, 

 which is here referred to as the " vis essentialis," is 

 elsewhere included under the expressions " vitality," 

 and "general determining laws of the organism." 

 Though this admission is seemingly so at variance 

 with the views of the same observer at the present 

 date (1870), who in common with other physicists 

 emphatically denies the existence of " vital force," 

 or even such a thing as life itself, yet, as already 

 intimated, we deem it possible to detect a fore- 

 shadowing of his more modern views, in the follow- 



* Beale, Microscope in Medicine. Third Edition. London : 

 1867, page 147. Beale, Structure and Growth of the Tissues. 

 London : 1865, pp. 9, 10. 



