Macronuclear Dissolution. 



291 



ber 6, 191 3) was observed during endomixis which in any way even 

 suggested ribbon formation and a figure was given of this animal 

 with the legend "An atypical form of macronuclear disintegration, 

 slightly resembling the ribbon-like formation characteristic of 

 conjugation." 4 



It is therefore interesting to record that the study of animals 

 from this same pedigree culture (I) of Paramecium aurelia at about 

 the 8900th generation (November, 1921) showed some cells 

 successfully undergoing endomixis with macronuclear disintegra- 

 tion by ribbon formation and others by chromatin-body formation. 



Thus it is clear that although all the data thus far at hand 

 indicate that chromatin-body formation is the typical method of 

 destroying the macronucleus in endomixis, nevertheless under 

 certain unknown conditions the formation of chromatin-ribbons, 

 until now regarded as diagnostic of conjugation, occurs in endo- 

 mixis. This fact, of course, in nowise narrows the significant and 

 crucial difference between endomixis and conjugation — the absence 

 of synkaryon formation in the former and its presence in the latter. 



129 (1876) 



Nutritive factors in plant tissues. V. Further observations on 

 the occurrence of vitamin-B. 



By THOMAS B. OSBORNE and LAFAYETTE B. MENDEL. 



[From the Laboratory of the Connecticut Agricultural Experiment 

 Station, and the Sheffield Laboratory of Physiological Chem- 

 istry in Yale University, New Haven, Conn.} 



In the course of our studies of the distribution of vitamins in 

 plant products we have collected data regarding a number of 

 important edible foods for which no information in this respect 

 seems to be available at present, with the possible exception of 

 indirect suggestions obtained by other than animal feeding trials. 

 Our experiments, made with rats, supplement numerous earlier 

 ones 1 conducted by the same technique and indicate that asparagus, 



4 Woodruff and Erdmann, loc. cit., Plate 4, Fig. 37. 



1 Osborne, T. B., and Mendel, L. B., Jour. Biol. Chem., 1919, xxxvii, 187; xxxix, 

 29; 1920, xli, 549; xlii, 465. 



