SCHWANN'S CYTOBLASTEMA. 25 



substance, in which new cells are to be formed, he 

 states that it may exist within ready-formed cells, 

 and outside of them, before they are formed ; that it 

 is the matrix and also the nourishment of cells ; that 

 it draws its own nourishment from the blood, but that 

 it differs chemically in different parts from that blood, 

 although how that difference is produced he does not 

 explain, for it is afterwards referred to the metabolic 

 power of the future cell wall and nucleus. Moreover, 

 the cytoblastema is said to possess vitality in various 

 degrees, but that may also be totally destitute of it, 

 as, for example, a boiled infusion of malt is said to be 

 the cytoblastema of yeast cells. Now, if we subtract 

 from these opinions what relates to the implied origin 

 of living cells from dead chemical matters, which part 

 has been eliminated by nearly all men of science, we 

 find that the primary formative matter is a structure- 

 less substance, possessing vitality, and proceeding 

 from pre-existing living matter. And it will not be 

 difficult to explain the confusion of the above statements 

 by the simple supposition that portions of it (even if 

 too minute to escape detection with the then existing 

 microscope) were present or not in the different cir- 

 cumstances : and we may thus reconcile the observa- 

 tions of this great pioneer with the discoveries of 

 future investigators. Let us see how far this is borne 

 out by the subsequent history of this structureless 

 living matter. 



The first notice of what appears to be identical with the 

 structureless living matter of Schwann, and the irritable or 

 living matter of Fletcher, is found in a memoir by Dujar- 

 din, in vol. iii. of the " Annales des Sciences Naturelles," in 



