178 THE VITAMINS 



deserve the name of odontoblasts any longer, as they are not forming 

 dentin, but bone in the form of an irregular network." Similar changes 

 except for a difference in color are apparent in the sections stained by 

 the Hansen method. 



In Hojer's opinion the error in the determination is not over 10 

 per cent and fairly accurate estimates may be made in tenths of the 

 protective dose, although it is advisable to determine the minimum pro- 

 tective dose, since this is more sharply defined. The chief advantages 

 of the new method as compared with the old are considered to be the 

 accuracy * in fixing the fully protective dose and the saving in time 

 and expense. 



Goettsch (1928) subjected the Hojer method to critical examina- 

 tion, particularly to determine whether the histological changes in the 

 teeth are specific for scurvy and how the results obtained by this method 

 compare with those of the method in general use. Her conclusions were 

 that the changes are specific for scurvy and that it is possible by this 

 method to determine the minimum protective dose, but that such varia- 

 tions occur within a group of animals on an inadequate dose that its 

 quantitative value can be determined only with the use of large numbers 

 of animals, using orange juice as the standard antiscorbutic, she 

 found that twice as much was required for the minimum protective 

 dose by the new method as by the old. Another advantage mentioned 

 by Goettsch in the new method as compared with the old is that with 

 the time of feeding shortened to two weeks there is less danger of 

 the animals dying from other causes than scurvy during the course of 

 the test. For those interested in this test, this paper of Goettsch, which 

 includes an appendix by K. M. Key giving the details of the technique, 

 is recommended as furnishing more explicit directions for conducting 

 the test than are given in Hojer's paper. 



Eddy (1929) has recently reported his experience in comparing 

 the Hojer method with that in general use. Using canned string beans, 

 orange juice, and bananas as the materials to be tested by the two 

 methods, he found, in agreement with Goettsch, that almost exactly 

 twice as much is required for the minimum protective dose for the 

 teeth as for protection against scurvy as previously understood. Com- 

 menting upon this, Eddy states : "It seems hardly possible that this 

 ratio is entirely fortuitous. If further tests establish it as the true 

 difference between tooth and general body requirements it will be a 



* It is to be remembered, however, that this "accuracy" may mean delicacy rather than 

 dependability, since it rests on a single criterion whereas the method previously described 

 employs the broader basis of a composite of criteria as the basis of judgtment of the degree 

 of scurvy, or of its absence. 



