LIVING AND NON-LIVING MATTER. 183 



differences of state, structure, and composition may be 

 denied by implication or ignored, these differences cannot 

 be destroyed; and every one who really desires to learn 

 anything about the structure, growth, and actions of living 

 things will find himself compelled to admit their existence, 

 and will at once proceed to inquire how they are to be 

 accounted for. No tissue of the body is destitute of living 

 matter, and, in almost all cases, particles of living matter 

 are very freely distributed, being separated from one another 

 by but thin layers of non-living tissue. 



In my lectures at the Royal College of Physicians, in 

 the spring of 1860, I pointed out that, in the tissues of 

 plants, animals, and man, both in health and in disease, 

 matter in the two different states above referred to was 

 invariably present, and I showed that every normal and 

 abnormal cell or elemental unit of every tissue capable of 

 growth, or possessing formative power, invariably consisted 

 of matter in these two states* or conditions: i. Living, 

 active, formative; 2. Lifeless, passive, formed. In my 

 preparations these two different forms of matter are at once 

 distinguished, the first having been artificially coloured 

 by alkaline colouring matter, and particularly by carmine 

 dissolved in ammonia, while the matter in the last condition 

 is untinged, although it has been freely traversed by the 

 coloured fluid. 



There are practical difficulties in carrying out the process 

 in some cases, and in my works on the microscope I have 

 described how some of these may be surmounted. The 

 plan of investigation has been spoken of contemptuously, 

 and many careless statements have been made concerning 

 it to which it is unnecessary to advert here. Many ob- 



