EFFECT OF STUNTING ON THE GROWTH IMPULSE. 



75 



EFFECT OF STUNTING ON THE GROWTH IMPULSE. 



Before proceeding to study the influence of dietary variations on 

 (a) maintenance and (b) growth, respectively, it became necessary to 

 learn whether a more or less temporary inhibition of growth checks 

 or in any degree modifies the capacity to grow (Wachstumstrieb) . 

 The literature on this subject by no means reveals a unanimity of 

 opinion, although familiar experience will bring to mind many illus- 

 trations of compensated retardation of growth in children.* A few 

 typical experiments may be cited. Rat 36 (male) kept stunted 49 

 days on a diet of gliadin foodf (37 days) followed by casein food mix- 

 turef (12 days), showed complete recovery of growth on a mixed diet 

 (see Chart XCVI). The "mixed diet of our animals consists of dog 

 biscuit, sunflower seed, and fresh carrots (with occasional changes 

 and addition of lumps of rock salt) . Rat 65 (female) stunted, during 

 33 dayson adiet of casein-zein food,! likewise resumed anormalrateof 

 growth as soon as the mixed diet was instituted (see Chart XXXVII) . 



Special interest is attached to experiments in which after a pre- 

 liminary stunting period the resumption of growth was accomplished 

 on a diet containing milk as the effective component. Two protocols 

 of the diet during the stunting period are reproduced in Table 

 XXXV, with reference likewise to Charts XXVIII and XXIX. 



Table XXXV. 



Duration of stunting 



Rat 64 (female), 

 33 days. 



Rat 51 (male), 

 46 days. 



Stunting diet. 



Casein 

 *Zein 



Starch 



Sugar 



Agar 

 fSalt mixture I 



Lard 



per cent 

 12.0 

 6.0 



29.5 



15.0 



5.0 



2.5 

 30.0 



Casein 

 Starch 

 Sugar 

 Agar 



fSalt mixture I 

 Lard 



per cent 

 18.0 



29.5 



15.0 



5.0 



2.5 

 30.0 



*The zein was hydrated by the addition of a little water. |Cf., p. 86. 



The curves in these cases are seen to be quite comparable with 

 those of the normally growing rats. Bearing inmind that the animals 

 here studied were continually kept in small cages under actual experi- 

 mental conditions, the "normal" character of the growth curves 

 makes it evident that the environment is no wise detrimental. 



*Cf. Condereau: Recherches chimiques et physiologiques sur I'alimentation des 

 enfants, Paris, 1869; Pagliani: Giornale della reale societa italiana d'igiene, Milano, 

 1879, 1. (Quoted by Hatai: American Journal of Physiology, 1907, xvm, p. 320.) 



fSee p. 122. 



I See p. 98. Water was added to this mixture until the zein was well hydrated. 



