472 EXPEHIMKNI" STATION KEC'OED. 



According to the analytical studios reported, 01 calories, or two-thirds of 

 the energy value of the total egg was required in the incubation process, of 

 which 23 calories was used for the development of the chick and measurable 

 as heat, and 38 calories was represented by the material in the chid s body. 

 The egg yolk romainhig unused at the time of hatching had an energy value of 

 2G calories or about one-third of the amount originally present. 



The values, therefore, per gram body weight of the chick would be O.son 

 calorie manifested as heat, that is, " relative energy of development," and 3.6 

 calories per gram dry matter, for body development, that is, "specific energy 

 of development." 



The energy required for development is largely supplied by the egg fat. No 

 nitrogen is lost during incubation, according to the authors, at least none could 

 be measured in their experiments. 



The assimilation of phosphorus and calcium by the chicken embi-yo, E. 

 Carpiaux {Acad. Roy. Brl</., Bui. CI. Hci., 1908, Xo. 3, pii. 2S3-2f)o; iihs. in Chciu. 

 Zcntbl., 1908, II, No. //, ji. 337). — lu continuation of earlier work (E. S. R., 15, 

 1>. G4) the author studied the calcium and organic and inorganic phosphorus 

 'ccmtent of eggs at different stages of incubation and found that as the embryo 

 develops the calcium and inorganic phosphorus of the egg increases while the 

 lecithin is correspondingly diminished. According to the observed data the 

 chicken uses almost entirely the phosphorus of lecithin for building its body 

 and does not make use of the phosphorus in the egg-shell. On the other hand, 

 the shell furnishes more than 80 per cent of the necessary calcium. 



Carbon dioxid under sitting" hens, H. D. Edmond (Connecticut Storrs Sta. 

 Rpt. 1907, pp. 157-162). — Using a modification of Pettenkofer's titration method, 

 the author found that the carbon dioxid under hens sitting on good eggs in 

 starch ranged from 3.8 to 22.5 parts by weight in lO.OUO parts of air while the 

 j)roportions in the air of the barn ranged from 2.8 to 5.2. Under a hen sitting 

 on china eggs the range was from 3.4 to 8.5. In tests in July, made by a some- 

 what different method, the percentages of carbon dioxid under hens were much 

 higher than in ]March, ranging from 5.3 to 12.0 with china eggs and from 9.0 to 

 80.1 parts per 10,000 of air with good eggs. 



In an "incubator samples of air were drawn by an aspirator from over the egg 

 tray, the parts of carbon dioxid ranging from 4.8 to 29.5. Oats was sown in one 

 pan to test the effect on the air of the incubatcu- of the carbon dioxid given off 

 by sprouting seed, but no noticeable difference was found. 



" Whether carbon dioxid is essential to a perfect hatch and vitality in a chick 

 is still an open question. This work is not complete enough to settle the ques- 

 tion and there is very little data to be found on this subject. It is true that 

 there is a much larger percentage of carbon dioxid imder sitting hens than in an 

 incubator. It is also true that hens hatch chickens with greater vitality than an 

 incubator." 



Incubation experiments, J. Dryden (Oregon. Sta. Bill. 100. pp. 3-32. figs. 

 G). — A series of investigations was started to test the relative efficiency of nat- 

 ural and artificial incubation and to discover improvements in incubation and 

 brooding. 



" From 879 eggs set, incubators hatched 533 chicks. t)r <;0.(:> per cent. I'rom 

 279 eggs, hens hatched 219 chicks, or 78.8 per cent. Elimiuiiting eggs broken in 

 nests, the hens hatched 88.2 per cent of eggs set. The incubators hatched 78.5 

 per cent of ' fertile " eggs, and the hens hatched 96.5 per cent. 



"Eggs incubated artificially tested out 22.7 i)er cent as infertile, while those 

 incubated by hens tested out 11.8 per cent. The incvibators showed 10.6 per cent 

 of chicks ' dead in the shell,' and the heus 2.8 per cent. 



