DR. BEALE^ ON THE TISSUES. 91 



No attempt has been made to define exactly what is an 

 indicidiucL It seems to me that as the several component 

 parts of the organism of the higher animals are dependent 

 upon each other for their existence, we cannot look upon 

 any one elementary part as an independent growintf living 

 structure. The conditions necessary for its existence are such 

 that it cannot live when detached. On the other hand the 

 contents (germinal matter) of what appears to be an elemen- 

 tary part (cell) of a simple fungus may be divided perhaps 

 into many thousand particles, every one of which is capable 

 of existing independently, of growing infinitely, and of pro- 

 ducing a structure resembling that from which it has sprung. 

 I have brought forward evidence favourable to the view that 

 li-vdng particles exist which are far too minute to be seen by 

 any magnifying powers which have yet been made. Again, 

 there are many instances in which division can be carried to 

 a certain degree of minuteness with the production of a 

 multitude of living particles, each one of which grows into a 

 structure resembling that of which it was but a small part. 

 Eut if the structure be divided into more minute particles 

 the death of all results. The simpler the conditions necessary 

 for existence the more independent are the several parts or 

 particles of which an organism is composed. As far as 

 structure is concerned, an elementary part of a fungus cor- 

 responds to an elementary part of one of the higher tissues. 

 The germinal matter of each is capable of grovvdng infinitely 

 and may be divided into numerous smaller particles, each 

 one of which is capable of growth, but the conditions 

 necessary for maintaming the vitality of the fungus are so 

 simple that each particle will live although separated from 

 its neighbours and exposed, within certain limits, to varia- 

 tions of temperature, moisture, &c. The particles of the 

 germinal matter of the elementary part from any tissue of 

 one of the higher animals, will only live when in contact with 

 the fluids of the body which produced it or those of another 

 body of the same kind. It cannot exist independently for 

 any length of time, and if the conditions under which it is 

 placed normally, be very slightly altered, it dies. Under no 

 circumstances can it produce an independent organism. 

 Neither a portion of germinal matter nor an entire elementary 

 part of a tissue of one of the higher animals can be regarded 

 as an independent structure. It is only a part of an indi- 

 vidual whole. On the other hand, a very small portion, far 

 too minute to be seen by the highest powers, of one of the 

 simplest and lowest forms of existence is independent, may 

 produce, though isolated, a structure similar to that from 



VOL. II. NEW SER. G 



