PHYSIOLOGY. 



PORTER, DAVID D.XoN. 743 



ubjccted lo tin- i-\i n-i-i- Mir\ivi-il. Siini- 

 lur result-, wen- uliiniiifil in other modified ex- 

 periments, nil leading to the conclusion that 

 MiM-eptibdity i> increased by fatigue. 



. i-i. > of ex|>eriinents is reported by Herr 

 Ruhncr on the difference with wliit-li dry hrat 

 ami cold ami moist In -at .-in- born ly the animal 

 ami human constitutions. 1 logs, fasting or led, 

 being observed in an air calorimeter, it appeared 

 that moist air im-iva-ed the loss of heat by con- 

 tluction and radiation. For every variation of 1 

 prr cent, in tin- air moisture, hrat was parted 



With to the extent of (Mfci ptTcrllt. Ill a prrVJollS 



iiiM-siigation llrrr Hubner had demonst rated the 

 lessened yield of water by evaporation from 

 animals \\ln-n the air moisture is increased, in- 

 volving lessened loss of heat. Here, then, are 

 two antagonistic inilneiiccs. The author is in- 

 clined to regard the increased radiation and con- 

 duction in the open air as the primary action, 

 ami the diminished evaporation as secondary. 

 The colder feeling of moist cold than dry is 

 readily explained by the increased hrat radiation. 

 In nioi-t heat, with the sense of oppression it 

 brings, this factor passes into the background. 

 The degree of temin'rature, nnd some outer in- 

 fluences of complex nature, also affect the 

 amount of radiation. 



The investigations by Eeidenhain of the flow 

 and production of lymph tend to the support of 

 the theory that the supply of lymph to the 

 tissues is derived from a secretion, as against 

 that which regards it as a filtration from the 

 blood. Among the considerations cited in sup- 

 port of this view are the amount of lymph that 

 has to be furnished under certain conditions, 

 certain influences of changes in arterial or 

 venous pressure causing conditions not in ac- 

 cord with any nitration theory; and the dis- 

 covery by the author of the existence of 

 " lymphagogues" substances which increase the 

 lymph flow either by causing a direct secretion 

 from the blood, or by withdrawing water from 

 the tissues and sending it into the lymph and 

 into the blood. In the increase of the lymph 

 flow under the operation of lymphagogues of tne 

 first class, a quantitative comparison shows that 

 the lymph has gained water and organic sub- 

 stances, but not salts, and that the blood plasma 

 has lost water and organic substances. That 

 this transfer of material is no filtration, is shown 

 by the fact that when the Mood flow has been 

 shut off for some time the introduction of 

 organic substances cause 1 * no increase in the 

 lymph flow the prolonged anaemia, it is a*- 

 suinrd. having altered the cells whose activity is 

 involved. To the second class of lymphagognes 

 belong sugar, urea, and salts when sent into the 

 blood in considerable quantities. Such sub- 

 stances leave the blood rapidly, as others had 

 shown, and the blood gains water. But the in- 

 troduction of grape sugar or sodium chloride also 

 enormously increases the amount of lymph and 

 the flow of urine from the kidney. Since the 

 amount of water in the blood, in the lymph, and 

 in the urine becomes greater, it follows that this 

 "sugar lymph " can have no other source than 

 the water of the tissues ; it is tissue lymph, and 

 not blood lymph. The experiments suggest that 

 the action of many saline waters mav be due to 

 such movement of the lymph as is shown in 



tliem, which may be thought lo purge and 

 purify tin- tissues without the nrdiimn purging 

 action of the salt- U-i:ig an important It-aim, at 

 all. 



The way in which altered plant pigment* take 

 part in larval coloring ha* In-cn under in\< 

 tion by K. li. I'oulson. 'I he earlier experiments 

 indicated that the green ground < olor of larva* 

 of certain species was due to derived green pig- 

 ments dissolved in the blood, while it was argmd 

 that in other specie.-, the pigments passed from 

 the blood into the hypodermic ccll.s and so 

 colored the larva?. It was still uncertain whether 

 the color of the blood assisted in producing any 

 of the ground color in those hir\a- in which the 

 color was also segregated in the hypodermic cell*. 

 The author's later investigations with the larva of 

 Sphinx ocellahis have shown that the blood is 

 only faintly tinged with derived pigments, and 

 that it can not produce any effect upon the lanal 

 appearance until it has been collected in the 

 superficial cells. The fact that the derived pig- 

 ment is associated with a proteid in the 1-1. . d 

 makes it almost certain ttiat the processes of 

 modification and association are the direct re- 

 sults of protoplasmic activity, and not of fer- 

 ments, etc., which have themselves been formed 

 by that agency. 



Dr. F. Maas describes two chemically distinct 

 groups of pigments occurring in man melanine 

 and granular coloring matters. The latter are 

 found at all periods of life, but increase in quan- 

 tity and in the size of the granules with age. 

 They are normal products, not morbid ; are not 

 only transformed, but are produced by corpuscle- 

 carrying cells, and are not wholly derived fn m 

 the blood. The pigment found in the heart is de- 

 rived from a fatty body. The several pigments 

 can be distinguished by their reactions with 

 hydrochloric and acetic acids, and with caustic 

 potash. 



Experiments are described by Dr. Yatsuty. of 

 Zhitomir, Russia, on the influence of age on the 

 rapidity of absorption of drugs. The author 

 gave iodide of potassium orsalicylate of soda, in 

 doses proportioned to the weight of the individ- 

 ual, to healthy male subjects of ages ranging 

 from eight to over eighty years. The urine was 

 examined every three minutes in the case of 

 both salts, and the saliva every two minutes in 

 the case of the iodide while no evidence of sali- 

 cylic acid was detected in the saliva at any time. 

 The general result of the tabulated experiments 

 showed that absorption occurred more rapidly in 

 the vounger persons in proportion to their youth. 

 but wide variations occurred in comparing indi- 

 viduals: so that although the average rapidity of 

 absorption was found to diminish distinctly as 

 au'e advanced, it was not possible to say with 

 icrtaintv that a particular person won hi absorb 

 one of the drugs more rapidly than a person who 

 was a good deal older. 



PORTER, DAVID DIXON, an American 

 naval officer, born in Chester. Pa., June 8, lH:i : 

 died in Washington. !>.('.. Feb. 18. 1891. His 

 great-grandfather commanded a Boston mer- 

 chantman, and rendered substantial assisUim e to 

 the colonies during the Revolution: his grand- 

 father commanded with distinction two Conti 

 nental vessels in the same war: and the Ml 

 of his father during the war with England in 



