The results just discussed were obtained with men in good health, from 17 to 40 years of age. Unfortunately the observations of the metabolism of individuals over 30 years of age are not so extended as they should be; we are thus unable to state definitely that the lowering of the metabolism noted in practically all instances with people of advanced years had not already begun with the subjects about 40 years of age, but our evidence thus far obtained does not lead us to infer this.

In any attempt to draw general conclusions from these short-period experiments we should depend more especially upon the values found for the oxygen consumption, as, being uninfluenced by the previous diet, they give a clearer picture of the actual metabolism. A general review of the results in tables 37 to 42 and of the results from which the average values in tables 43 to 45 are drawn shows that with all of the subjects the individual values fluctuated considerably at times, but that the average values from period to period indicate no general change one way or the other. The average values for the experiments during a period of several months or years show a general constancy in the metabolism, there being but few average values which vary widely from the general average for the whole period. This is emphasized by the fact that the general mean variations for the various subjects were not large. The general constancy in the metabolism during the different hours of the day and during different months and years thus seems to be fairly well established by these data, at least for individuals between 17 and 40 years of age.

The variations in the individual values make clear the fact that single determinations should not be relied upon and that in order to obtain a value for the basal metabolism it is necessary to secure two or three well-agreeing periods for averaging. Inasmuch as the average values from period to period did not tend to change in any one direction, they were evidently free from diurnal influence; this factor may therefore be eliminated in considering the results of comparison experiments in which the metabolism during fast is first determined and subsequently the metabolism after food. This leads us, therefore, to the general conclusion that the determination of basal values immediately prior to the ingestion of food is the most logical and satisfactory method for studying the small changes in the metabolism frequently noted after the ingestion of food.

Table 45. - Gaseous Metabolism At Different Times Of Day In Respiration Experiments

Subject, naked weight,1 height, age.1

Time covered by experiments.

Observation.

First half hour.2

Second half hour.

Third half hour.

Fourth half hour.

Fifth half hour.

Sixth half hour.

Seventh half hour.

Eighth half hour.

H. R. R.

69.5 kilos, 185 cm..19 yr.

1 periods, Apr. 22, 1915, to April 23, 1915.

Avg.CO2.

c.c. 216

c.c.

208

c.c. 211

c.c.

c.c.

c.c.

c.c.

c.c.

Avg. O2..

278

272

270

[Days.....

2

2

2

A. J. 0. 69.3 kilos, 180 cm., 30 yr.

100 periods, Nov. 4, 1914, to Feb. 8, 1915.

Avg.C02.

216

214

208

207

206

202

208

200

Avg. O2..

252

250

247

247

254

247

259

241

[Days. . . .

6

22

20

13

4

3

2

1

K. H. A.

66.4 kilos, 182 cm., 26yr.

139 periods, July 27, 1911, to June 26, 1912.

Avg.CO2.

2033

189

185

197

192

194

194

193

Days.....

1

1

3

12

23

19

18

12

Avg. 02. .

2523

228

241

241

242

238

236

238

Days. . . .

1

1

2

12

23

18

18

12

J. R. 66.0 kilos, 182 cm., 27 yr.

54 periods, Feb. 25, 1909, to June 2, 1909.

Avg.C02.

2313

211

213

202

199

200

204

200

Days.....

1

1

4

7

10

7

6

6

Avg. 02. .

2523

244

237

242

244

246

244

245

Days....

1

1

4

8

9

7

6

6

J. J. C.

65.0 kilos, 175cm., 26 yr.

258 periods, Feb. 26, 1909, to Apr. 25, 1911.

Avg.CO2.

194

193

191

193

189

188

189

191

Days. . . .

2

12

37

38

42

29

26

24

Avg. O2. .

241

229

231

230

229

225

227

229

Days.....

2

11

35

38

40

28

24

23

H. W. F.

58.0 kilos, 174 cm., 25 yr.

41 periods, Jan. 27, 1915, to July 30, 1915.

Avg.C02.

178

162

164

172

Avg.02..

224

205

210

223

(Days.....

3

5

2

1

H. F. T.

57.8 kilos, 179 cm., 32 yr.

272 periods, June 8, 1911, to Jan. 30, 1912.

Avg.C02.

1684

158

158

173

168

172

171

167

Days....

6

9

10

11

19

28

20

27

Avg. O2. .

2004

191

192

195

198

193

194

194

Days.....

6

7

9

11

20

27

20

26

V. G.

54.7 kilos, 162 cm., 17 jr.

63 periods, Nov. 4, 1910, to Mar. 11, 1911.

Avg. C02.

201

194

190

197

198

219

204

190

Days.....

6

11

11

9

4

1

5

1

Avg. 02. .

240

229

228

229

236

233

231

230

Days.....

6

11

11

9

4

1

5

1

T. H. H.

54.5 kilos, 171 cm., 29 yr.

44 periods, Feb. 17, 1915, to Mar. 31, 1915.

Avg.C02.

176

179

182

175

167

Avg. 02..

205

205

207

199

199

Days. . . .

3

10

10

4

1

W. K.

49.7 kilos, 162 cm., 29 yr.

39 periods, Feb. 20, 1915, to July 16, 1915.

Avg. C02.

167

169

164

163

Avg. 02. .

196

200

194

201

[Days.....

3

6

5

1

T. M. C.

48.5 kilos, 165 cm., 32 yr.

100 periods, Mar. 23, 1909, to May 27, 1914.

Avg. C02.

168

157

154

152

152

153

155

156

Days.....

4

10

13

17

15

14

11

9

Avg. O2. .

183

188

184

183

180

183

187

188

Days.....

4

9

14

14

14

14

10

9

1Average body-weight and average age for the series of experiments.

2The experimental periods were usually 15 minutes in length and in most instances there was but one period in the half hour. The average time of the first period used was at all times approximately between 8 a. m. and 9 a. m., except as otherwise noted.

3The average time of the first period with this subject was 7 a. m.

4The average time of the first period with this subject was 6h30m a. m. subjects in post-absorptive condition and lying on couch. (Values per minute).

Ninth half hour.

Tenth half hour.

Eleventh half hour.

Twelfth half hour.

Thirteenth half hour.

Fourteenth half hour.

Fifteenth half hour.

Sixteenth half hour.

Seventeenth half hour.

Eighteenth half hour.

Nineteenth half hour.

Twentieth half hour.

Twenty-first half hour.

Average of daily averages.

Subject, naked, weight,1 height, age.1

ex.

c.c.

c.c.

c.c.

C.C.

c.c.

c.c.

ex.

ex.

c.c.

c.c.

ex.

c.c.

c.c.

218

219

209

213]

H. R.R.

69.5 kilos, 185 cm., 19 yr.

289

292

285

280

1

2

2

2

199

205

212

203

205

210]

A. J. O. 69.3 kilos, 180 cm., 30 yr.

247

251

252

247

254

249

1

2

3

4

4

24,

198

190

194

194

194

190

201

194]

K. H. A.

66.4 kilos, 182 cm., 26 yr.

11

13

10

4

4

2

2

28

237

232

236

235

242

236

240

239

11

13

10

4

4

2

2

28

207

199

188

202]

J. R.

66.0 kilos, 182 cm., 27 yr.

6

3

2

12

245

253

240

243

6

3

2

12.

191

189

188

193

196

208

206

204

191

191]

J. J. G. 65.0 kilos, 175 cm., 26 yr.

16

8

3

3

2

1

2

4

3

52

234

234

237

242

229

243

233

240

240

230

15

7

3

2

2

1

2

4

3

52J

168

172

185

180

176

171

172]

H. W. F.

58.0 kilos, 174 cm., 25 yr.

206

211

231

224

217

213

214

2

2

1

3

4

4

9

161

165

156

163

153

159

157

159

149

155

156

158

167

165]

H. F. T.

57.8 kilos, 179 cm., 32 yr.

16

20

15

16

11

9

10

10

3

4

3

3

3

44

189

194

185

187

179

186

185

190

181

190

189

189

188

192

16

19

15

16

11

9

10

10

3

4

3

3

3

44

198

196

195

191

199

195]

V. G.

54.7 kilos, 162 cm., 17yr.

3

4

2

3

3

14

231

240

230

233

233

231

3

3

1

3

3

14

188

185

183

186

180]

T. H. H.

54.5 kilos, 171 cm., 29 yr.

. .

. .

226

220

217

206

207

2

5

4

2

12

151

159

166

169

178

170

175

165

168]

W. K.

49.7 kilos, 162 cm., 29 yr.

166

192

199

205

217

190

202

197

200

1

3

5

3

1

1

2

2

8

161

165

162

154]

T. M. C.

48.5 kilos, 165 cm., 32 yr.

3

2

2

18

196

188

190

184'

4

2

2

18