PHYSIOLOGY, RECENT. 



749 



tion of the vessels of the skin is capable of be- 

 ing regulated independently of the cerebro-spi- 

 nal vasomotor centers. It is not clear what is 

 the nature of this mechanism, but it seems to 

 he adequate to measure out the degree of dila- 

 tation according to the requirements of the tis- 

 sues, and appears to be the same that is called 

 into action under the application of irritants. 

 The capillary vessels have been shown to be 

 capable of varying their diameters independ- 

 ently of one another. The conclusion is logic- 

 ally derivable that each capillary is capable of 

 varying its caliber in accordance with the re- 

 quirements of the tissues which it supplies with 

 blood. To this automatic regulation of the 

 peripheral circulation Professor Eay is in- 

 clined to ascribe a function of great impor- 

 tance, both from a physiological and a patho- 

 logical point of view ; and it appears that it is 

 principally, if not exclusively, in connection 

 with it that the contractility of the capillaries 

 comes into play. 



Dr. J. N". Langley, of Trinity College, Cam- 

 bridge, has brought the subject of the histolo- 

 gy of the gastric or pepsin-making glands be- 

 fore the Royal Society, in a paper in which ho 

 has sought to collate the proofs, from his exper- 

 iments, that the gastric glands in life contain 

 no ferment, but much zymogen or substance 

 capable of giving rise to ferment ; that by far 

 the greater part of the zymogen can be seen in 

 the chief cells in the form of granules; and 

 that during digestion the granules are usually 

 used up in such a manner as to give rise to an 

 outer non-granular and an inner granular zone 

 in the chief cells. These points, if proved, would 

 establish fundamental resemblances in life-hab- 

 it between the chief cells of the gastric glands 

 of mammals, the cells of the gastric glands of 

 the lower vertebrates, and the cells of the pan- 

 creatic gland. It was found that the chief-cell 

 granules of some mammals are preserved by 

 osmic acid, while those of others are not. The 

 examinations were made chiefly with prepara- 

 tions of the former class, and were checked by 

 comparison with glands in the fresh state ; they 

 related to the border cells and the chief cells 

 of different regions of the stomach. In both 

 the mouse and the mole, in the hungry state, 

 the chief cells are granular throughout; in the 

 digestive state, the chief cells have an outer 

 non-granular zone of from one third to one 

 half of the cell. In the Guinea-pig and the 

 rabbit the chief cells of the latter part of the 

 greater curvature show few or no granules; 

 in the median part of the greater curvature the 

 glands have usually an outer clear zone, which 

 diminishes in passing toward the fundus, while 

 in the fundus and in the adjoining part of tho 

 greater curvature tho chief cells are granular 

 throughout. During digestion an outer clear 

 zone is formed in the glands of tho latter part 

 of the fundus and tho fore part of the greater 

 curvature, while tho cells of the rest of tho 

 greater curvature lose more or less completely 

 their granules. Heidenhain first announced 



the conclusion that the chief and not the bor- 

 der cells produce pepsin. This is confirmed 

 by Dr. Langley's comparison of the pepsin con- 

 tents of the different stomach regions in sev- 

 eral animals. In each case the amount of pep- 

 sin found bore no relation to the number of 

 border cells, but almost always varied directly 

 with the number of chief cells. It was also 

 shown that in the different regions of the stom- 

 ach of the rabbit most pepsin is found where 

 the granules are most numerous. It is now 

 very generally accepted that pepsin exists in 

 the gastric glands partly free and partly com- 

 bined i. e., partly as pepsin and partly as pep- 

 sinogen. A series of experiments made with 

 especial reference to this point has convinced 

 Dr. Langley that pepsin, as such, does not ex- 

 ist in the living glands, but that in the animals 

 with which he worked, and probably in all 

 vertebrates, the gastric glands store up pepsin- 

 ogen and not pepsin. This is converted by 

 hydrochloric acid into pepsin. As far as our 

 knowledge goes, rennet - ferment is found in 

 greatest quantity where there is most pepsin, 

 and both vary pari pa&su. Perhaps, suggests 

 Dr. Langley, the granules of the chief cells may 

 contain zymogen both of pepsin and of ren- 

 net-ferment, and he offers this as a subject for 

 further observation. In all the vertebrates in 

 which the gastric glands have been carefully 

 examined in the living state, it has been found 

 that those gastric glands which produce most 

 ferment store up their zymogen in the form of 

 granules. The ferment-forming cells consist 

 of a net-work of protoplasm, inclosing a mass 

 of granules. It seems probable, on general 

 grounds, that the cells should store up other 

 antecedent substances besides zymopen, and 

 wo are not without facts which will tell in 

 favor of this view. In the saliva of many ani- 

 mals ferment is almost or entirely absent, but 

 mucin and proteids occur. We have sorao 

 proof that mucin arises during secretion from 

 tho splitting up of an antecedent substance, 

 mucigen, which is stored up in tho oil! ; in tho 

 serous salivary glands, and in tho lachrymal 

 glands, tho occurrence of grannies which are 

 used up during secretion, just as are tho gran- 

 ules of tho pancreas or o*f the pastrio glands, 

 makes it extremely probable that in those glands 

 sorao antecedents of tho proteids found in tho 

 secretion, not the actual proteids of the s 

 tion, are stored up. Apparently, then, a largo 

 number of gland-cells have tho feature in 

 mon that tho cell protoplasm forms certain 

 antecedent substances, which Dr. Lanploy pro 

 poses shall bo called "mesostates," which it 

 stores up, and that are converted, when secre- 

 tion takes place, into secretory products. In 

 tho pancreas the chief mesostato is trypsinogcn, 

 in the gastric plands it is popsinogcn, in tho 

 mucous gland* it is mucigen, etc. 



Observations made by UfFolmann on a pa- 

 t'u-nt upon whom pastrotomy had been per- 

 formed, have indicated that no hydrochloric 

 acid is secreted during tho earlier stages of 



