J 149 



That of ferments is still smaller: 



Pepsin gljceriii (sat.) 

 Diastase ,, ,, 



Paiicreatin 2 7o ^M- sol. 

 Leiu'iii 2 7o ^^■ sol. 

 Tyros ill sat. aq. sol. 



The following appeared to be irresponsive: 



Lecithin (sat. aq. sol.) and Casein (sal. aq. sol.), these materials 

 being neither sensitive to plioto-eleftricifv of themselves. 



The literature does not make mention of the Hallwachs etFect 

 on ge/s. 



We examined a series of gels and found sensitivity with some, 

 with others we did not. 



Of the first category the pure substance was also sensitive when 

 thoroughly dried and showed a powerful absorption of ultra- 

 violet rays. 



A positive reaction was observed with: 



Half- way -time 



Lighted Not lighted 



Physiological substances occurring in tissues partly in the gel- 

 condition, we tried to make a model imitative of that tissue. We 

 believe we have found it in a silicic acid gel, prepared by Prof. 

 Beyrrinck's method : 



10 c.c. of Na silicate, diluted with twice its volume of water is 

 shaken well and rapidly with 10 c.c. of normal hydrochloric 

 acid, and subsequently poured out into a Petri's dish, where soon 

 after a gel is formed, which is insensitive. 



Now if some colloidal solution is poured over the plate before 

 the mass has become quite firm, the gel-mass will be more or less 

 deeply imbibed, together with the liquid. 



The solution may also be treated with silicic acid gel before 



