GROWTH 7. FUNCTIONAL ACTIVITY 289 



cells. In other tissues the fully differentiated cells are capable 

 of division and proliferation, but this only after reversion to a 

 simpler type, or, as we term it, a more embryonic state, in which 

 evidently their functional secretory activity is reduced to a 

 minimum. Thus, after the injection of indigo-carmine, Mar- 

 tinotti x has pointed out that in a kidney, portions of which have 

 been removed in order to study the compensatory overgrowth 

 of the remaining part, all the cells of the convoluted tubules in 

 the remaining part take up the pigment, save and except those 

 in a condition of active mitosis : these remain perfectly colourless. 

 Even in so simple a tissue as connective tissue, the cells exhibit 

 this return to a more " embryonic " state prior to multiplication. 2 



Professor Carlier of Birmingham has, I may add, noted cases 

 apparently contrary to what is here stated ; cells of the gastric 

 glands may show mitosis and the appearance of secretory granules 

 in their protoplasm at one and the same time. 3 But these may 

 well be stored-up granules. In a letter to me — which in conse- 

 quence of the long time it would take to gain his necessary 

 permission, I trust I may be permitted to quote — he states that 

 in his opinion a dividing cell may be functionally active. He 

 adds, however, that when this is the case, he is inclined to believe 

 that the nuclear changes characteristic of mitosis become sus- 

 pended for the time being. 



Thanks to the researches of Hodge, 4 Mann, 5 and other neuro- 

 logists, of Macallum of Toronto, 6 and of his pupils, Scott and 

 Bensley, and of Carlier, and of other physiologists and cytologists, 

 we are recognizing more and more that the nucleus plays a con- 



1 Martinotti, Centralbl. f. allg. Path, i., 1890. 



2 Here let me urge that the use of this term '' embryonio " as applied to 

 cells in an adult organism is of questionable value, and indeed is responsible 

 for not a little of the want of comprehension of the phenomena of normal and 

 abnormal cell growth. I would suggest in preference the employment of the 

 term " vegetative " or " proliferous " to include the whole series of these cells. 

 For, strictly speaking, in these cases of reversion to a simpler state, it is a mis- 

 nomer to speak of adult cells becoming embryonic, and a continuance of or 

 reversion to this simpler histological condition is not an indication of an em- 

 bryonic condition, but is essentially correlated to the mode of activity of the 

 cell ; or, otherwise, the so-called embryonic cell is a cell which specially is in a 

 position to proliferate, and is not in a position to perform specialised fjmetfon. 



8 Carlier, British Medical Journal, September 15, 1900, p. 740. """ 



4 Hodge, Amer. Joum. of Psychol, iii., 1890, p. 530 ; Jourii.of Morphol. vii., 

 1892, pp. 99 and 449 ; Joum. of Physiol, xvii. p. 129, 1894. 



5 Mann, Joum. Anat. and Physiol, xxix. p. 100, 1895. 



6 A. B. Macallum, British Medical Journal, 1898, ii. p. 778. 



U 



