August, 1922 



SCIENTIFIC AGRICULTURE 



403 



cium metabolism since it brings about the 

 retention of lime and promotes its deposition 

 in the bone forming areas. A deficiency of 

 the vitamin on children results in a non- 

 assimilation and loss of lime and consequently 

 a deterioration, in skeletal metabolism and 

 production of rickets. This latter condition 

 is brought about more rapidly when, together 

 with a fat soluble deficiency, there is a low 

 plane of intake of lime and phosphorus. As 

 an antirachatic substance the principal re- 

 liance must be placed on crude codliver oil 

 which is specific for this condition and ac- 

 complishes almost miraculous results. The 

 "A" factor is also responsible for the good 

 condition of the developing dentition since a 

 mild deficiency will produce underdevel- 

 oped teeth and a predisposition toward caries. 

 Another feature due to a partial chronic de- 

 privation of this vitamin is the development 

 of keratomalacia. Formation of purulent 

 discharges of the cornea and conjunctiva 

 which may proceed so far as to involve com- 

 plete destruction of the eyeball and it was this 

 feature that first directed attention to the 

 presence of the fat soluble factor. 



It is only within the last decade that it 

 was considered that the process of growth in 

 adolescent animals could be influenced by 

 other factors than actual starvation. Rub- 

 ner's views that growth would take place if 

 a sufficient quantity of calories were sup- 

 plied of which 5 per cent, must be in the form 

 of protein had dominated the field. But dur- 

 ing the course of the investigation of the im- 

 portance of certain animo-acids instead of em- 

 ploying natural food stuffs, an artificial diet 

 was made up of a fat, carbohydrate, protein 

 and salt mixture which was found satisfactory 

 for growth experiments. Hopkins went a 

 step further and found that this apparently 

 pure mixture after further purification by ex- 

 traction of the protein. and sugar with alco- 

 hol did not enable the animal to grow, but de- 

 cline and death followed. The residue from 

 the alcohol extract when added to the mixture 

 again rendered it adequate. A further series 

 of experiments with the highly refined diet 

 mixtures showed that these enabled young 

 rats to grow if supplemented with 1-3 cc. 

 of milk daily per animal. This extra ration 

 was insufficient to account for the results 

 even from the standpoint of calorific energy 

 and Hopkins claimed that it was explained 

 by the presence of minute traces of some ac- 

 cessory in the milk which supplied the stim- 

 ulus to enable the growth process to proceed. 

 A series of experiments by other workers also 



indicated that this accessory was also present 

 in brewers' yeast and could be obtained from 

 a series of various natural food stuflFs which 

 were proven later to be carriers of the water 

 soluble antineuritic vitamin. Various at- 

 tempts to isolate the growth factor resulted 

 in the discovery that it could be separated 

 by phosphotungstic acid and certain adsorp- 

 tive media and showed these properties in 

 common with the "B" vitamin. It is now 

 considered to be identical with this latter 

 compound. 



Most of this work was carried out with 

 feeding experiments of short duration and 

 wli^n carried out for longer periods than 

 fifty days it developed that after about three 

 months the growth curve began to slow up 

 and recede, the animals developing keratomo- 

 lacia. Apparently another factor came into 

 play which neutralized the effect of the anti- 

 neuritic vitamin. Only after supplying the 

 ether soluble portion of butter fat did any 

 improvement occur and the animals approach 

 maturity and live the ordinary span of life. 

 This was the first indication and discovery of 

 the presence of the fat soluble vitamin and 

 further research localized this element in the 

 olein fraction of the butter fat. It is evi- 

 dent that unlike the "B" accessory the animal 

 can survive for a protracted period before 

 showing symptoms of a fat soluble defi- 

 ciency and that the requirements of growing 

 animals are keener than mature ones since the 

 deficiency symptoms appear much sooner in 

 the former case. 



In the earlier experiments with rats very 

 little account was taken of the effects of an 

 antiscorbutic deficiency since rats do not de- 

 velop the typical symptoms associated with 

 this condition. Subsequent experiments with 

 these animals indicate that growth approaches 

 maturity much more rapidly and the final 

 weight is greater if the antiscorbutic factor 

 is present in addition. to the A and B vita- 

 mins. Guinea pigs are more sensitive to the 

 antiscorbutic deficiency and when deprived 

 of this, even though the other two factors are 

 present in excess, soon cease to grow and lose 

 weight and ultimately develop scurvy. The 

 most recent method for detecting the anti- 

 scorbutic factor is by a study of the growth 

 curves of young calves which are fed bran, 

 oats, water and autoclaved milk (1 hr.). 

 This provides a normal diet and the A and 

 B factors and the antiscorbutic factor is as- 

 certained by feeding the material in question 

 and determining its effect in promoting the 

 orrowth. It is now universally conceded that 



