31 



and secondarily for vitamin Be. Ceratosfomella piceapcrda grows very slowly 

 in a medium of minerals, sugar and asparagine. The addition of biotin 

 and vitamin Be markedly increases its growth. While C. pseudotsugae 

 evidences partial deficiencies for Bi and Eg, C. piceaperda suffers from 

 partial deficiencies of biotin and Be- 



Ceratostomella ips isolated from Piniis ponderosa does not grow in the 

 basal medium. It sufifers from a biotin deficiency and on the addition of 

 biotin to the medium grows quite satisfactorily. C. fimbricata and the 

 Ceratostomella from London Plane have a complete Bi deficiency. C. nlmi 

 has a nearly complete Be deficiency. C. pini isolated from Pinus echinata 

 and C. pini isolated from Pinus ponderosa though differing somewhat in 

 appearance of growth are alike in having complete deficiency for both biotin 

 and Bi. C. montium and C. ips isolated from Pinus echinata suffer from 

 major deficiencies of Bi, Be and biotin. They grow little or not at all unless 

 all three vitamins are present in the medium. Among these ten species or 

 strains of Ceratostomella seven different types of vitamin deficiencies exist: 



1. Major or complete deficiency for Bi — little affected by Be or biotin. 



2. Major or complete deficiency for Be — little affected by Bi or biotin. 



3. Major or complete deficiency for biotin — little affected by Bi or Be. 



4. Partial deficiency Bi and Be — little affected by biotin. 



5. Partial deficiency biotin and Be — little affected by Bi. 



6. Major deficiency biotin and Bi — little affected by Be. 



7. Major deficiency Bi, Be and biotin. 



By selecting a suitable species of Ceratostomella it is possible by its 

 growth or failure to grow to demonstrate the presence or absence of Bi, Be 

 or biotin or substitutes therefor. In the course of these experiments it was 

 discovered by accident that an extract of cotton batting added to a medium 

 of minerals, sugar and asparagine permitted good growth of Ceratostomellas 

 which showed deficiencies for Bi, Be or biotin or combinations. It seems 

 justifiable to conclude that unbleached and unwashed cotton contains sig- 

 nificant quantities of all three of these vitamins. 



In the same way, that is by the growth of various species of Ceratosto- 

 mella, the presence of Bi, Be and biotin in unpurified Difco agar also was 

 determined. 



Since cotton and Difco agar are both commonly used in laboratory 

 procedures, it is clear that due consideration must be given to them as pos- 

 sible sources of vitamins. Knight and his associates working with the 

 so-called sporogenes vitamin found that stray filaments of cotton falling in 

 their media invalidated their bacterial experiments. 



In presenting these results I have emphasized the more marked deficien- 

 cies of the Ceratostomellas for the three vitamins Bi, Be and biotin. Less 

 marked deficiencies have been observed. For example, a species which grows 

 little or not at all unless Bi is added to the medium may grow somewhat 

 more rapidly if all three vitamins are added. It is probable also that some 

 of these organisms suffer from partial deficiencies for other vitamins or 

 vitamin-like growth substances. I am not sure that reproduction will occur 



