Theory of Gel Structure. 155 



be found that on expelling the jelly (which can be done with a 

 little practice by quick immersion of the whole tube in warm water) 

 the place of former heating is weak, and fractures readily. Indeed, 

 this region may look to the eye actually thinner. The cause of this 

 is to be found in the well-known hysteresis of jelly. That part 

 which is heated and allowed to reset, will melt more readily on 

 the application of the warmth necessary to loosen the jelly cylinder 

 in the tube. But if a cylinder of jelly is cut through slowly with a 

 platinum wire, carrying an adiustable electric current just sufficient 

 to produce melting of the jelly, a complete transverse lesion can be 

 obtained, which on resetting exhibits no weakness. If an ordered 

 arrangement of the solid phase was pronounced, one would expect 

 to find weakness always manifest, when continuity was once dis- 

 turbed. No definite conclusion can be based on this evidence, but 

 once more it points either to the lack of any vectorial character or 

 to such being of the nature of a complex of uniform cubical or rect- 

 angular units. 



l^he Struve-Baumstarh Phenonemon. 



In 1885 a method was described by F. Baumstarki of preparing 

 aqueous extracts of brain tissue for purpose of analysis. The pro- 

 cedure was simply to immerse the brain matter in ether, where- 

 upon after a day or two a copious watery extract was expelled from the 

 brain tissue, and collected at the bottom of the receptacle. Baum- 

 stark found that petroleum ether was without this effect. In reality 

 this phenomenon had been already observed and utilised in 1876 

 by H. Struve,2 who investigated the watery extract obtained from 

 various plant and animal tissues. The same device was resorted 

 to by MacMunn^ in order to obtain muscle extracts for the study 

 of myohaeniatin. 



I have made a number of experiments on this method, chiefly 

 from the standpoint of the structure of gels. 



One hundred grms. sheep's brain, immersed in wet ether, gave 

 in three days 37.5 cc. aqueous extract. After one week the amount 

 was 39.9 cc; after three weeks 41.4. The solid matter in this ex- 

 tract was 3.6%. 



One hundred grms. of meat fairly fat-free gave in one week 17.5 

 cc. extract. The solid matter was 4.2%. 



1 Zeit. f. physiol. Chemie. Vol. 9, p. 145. 1885. 



■2 Bull, de I'Ac.ad. Itnp. de St. Petersburg. Vol. n, p. 243. 1876. 



Also Bericht. rtentsch. cheni. Gesell. Vol. '.), p. 623. 1876. 

 3 .Iourn.ll of Phvsiol. Vol. S, p. 54. 1887. 



