MACDOUGAL AND SPOEHR— GROWTH AND IMBIBITION. 347 



The protein extract from the bean was thus shown to exert an 

 influence on the swelling of agar similar to that of egg-albumen in 

 reducing the amount of swelling in acid and alkali, and increasing 

 it in distilled water. 



The next step of importance was to ascertain the effect of some 

 of the simpler amino-acids which might be derived from the albumens 

 in the plant. Tyrosin and cystin were available. As an example 

 of the method the first preparation of tyrosin was one in which one 

 part of this substance in solution was stirred to a liquefied mass of 

 ten parts of agar at a temperature of 32° C. This was poured on 

 a glass slab, and as desiccation was carried out the tyrosin began to 

 collect as a flour-like efflorescence on the surface, and apparently a 

 large part of the substance came out in this way, so that the actual 



Fig. II. Auxographic record of swelling of sections of agar 90 — tyrosin 

 10, .15 mm. in thickness, in NaOH N/ioo, A = 133 per cent., in HCl N/ioo, 

 B =223 per cent., and in distilled water, C = 1600 per cent. X 6. 



proportion of the amino-acid in the dried plate was probably not 

 more than a fourth of the amount originally used. 



The dried plate of material came down to a thickness of .15 mm. 

 and gave the following results (Fig. 11) : 



Swelling. 

 Agar go — Tyrosin 10 (less by efflorescence). 



Water. HCl N/ioo. NaOH N/ioo. 



1600.0 per cent. 133.3 per cent. 133.3 per cent. 



1200.0 233.3 lOO-O 



Averages: 1400.0 183.3 116.6 



A similar preparation of agar and cystin gave the following as 

 an average of three tests : 



Agar go — Cystin 10. 



Water. HCl N loo. NaOH N/ioo. 



23333 per cent. 583.1 per cent. 328.6 per cent. 



