822 



SCIENCE. 



[N. S. Vol. V. No. 126, 



the sole factor. Experiments from Bizzo- 

 zero's laboratory, by Morpurgo and by 

 Penzo, indicate that local hypersemia due 

 to vasomotor paralysis, or to the appli- 

 cation of heat, favors cell multiplication in 

 parts where proliferation of cells is a nor- 

 mal phenomenon, or is present from path- 

 ological causes, but that it is incapable of 

 stimulating to growth cells whose prolifer- 

 ating power is suspended under physio- 

 logical conditions, as in developed con- 

 nective tissue, muscles and the kidneys. 



It has been usually assumed that the way 

 in which local hypersemia may stimulate 

 cell-growth is by increasing the supply of 

 nutriment to cells. The trend of physio- 

 logical investigation, however, indicates 

 that the cell, to a large extent, regulates its 

 own metabolism. If the cell needs more 

 food, of course, it cannot get it unless the 

 supply is at hand, and in this sense we can 

 understand how a larger supply of blood 

 may be essential to increased growth, but 

 this is a very diiferent thing from saying 

 that the augmented blood- supply causes 

 the growth. 



It is by no means clear that the question 

 as to the influence of increased blood-sup- 

 ply upon cell-growth is identical with that 

 of increased lymph-supply. The experi- 

 m.ents of Paschutin and of Emminghaus, 

 from Ludwig's laboratory, nearly a quarter 

 of a century ago, indicate that local hy- 

 persemia due to vasomotor paralysis does 

 not, as a rule, increase the production of 

 lymph ; and more recent experiments, al- 

 though not wholly concordant in their re- 

 sults upon this point, tend to the same con- 

 clusion. Functional activity, however, has 

 a marked influence in increasing the quan- 

 tity and affecting the quality of lymph in 

 the active part. Our knowledge of the 

 physical and chemical changes in working 

 muscles and glands enables us to conceive 

 why this should be so, for all are now 

 agreed that the formation of lymph is due 



not simply to filtration from the blood- 

 plasma, but also to diffusion, and some be- 

 lieve likewise to active secretion by the 

 capillary endothelium. Doubtless arterial 

 hypersemia is essential to the maintenance 

 of the increased flow of lymph in working 

 organs. 



There are difficulties in the way of sup- 

 posing that increased supply of lymph in it- 

 self furnishes the explanation of cell-growth, 

 and especially of that which characterizes 

 hypertrophy of muscles and glands. Pa- 

 thologists have frequent opportunities to 

 study the effects of all degrees of increased 

 production and circulation of lymph asso- 

 ciated with venous hypersemia. A kidney 

 or a muscle may from this cause be sub- 

 jected for months and years to an excess of 

 lymph-flow, but there is no demonstration 

 of any consequent hypertrophy or hyper- 

 plasia of renal epithelium or muscle-cell. 

 It is true that the chemical composition of 

 the lymph is not the same as that of lymph 

 resulting from increased function, and it is 

 possible that in this chemical difference lies 

 the kernel of the whole matter. It may 

 also be urged that in venous hypersemia 

 there are circumstances which restrain or 

 prevent growth. ISTevertheless, if overfeed- 

 ing, merely in consequence of increased sup- 

 ply of nutriment, were the real explanation 

 of work-hypertrophies, one would expect to 

 find some evidence of this in the class of 

 cases mentioned. 



Ribbert has recently given a new shape 

 to the doctrine that local hypersemia ex- 

 cites growth. While rejecting the usual 

 explanation that it does so by supph'ing 

 more food, he contends that distention of 

 the bloodvessels and lymph-spaces, by me- 

 chanically disturbing the mutual relations 

 of parts, removes obstacles to growth. This 

 theory cannot be advantageously discussed 

 until the fact is first established that un- 

 complicated local hypersemia does incite 

 growth. 



