1905.] Crystalloids and Colloids through Gelatine. 319 



Examination for Sodium Chloride. — Experiment No. 1, Table L 

 Original Fluid : 0"88 per cent. NaCl represented as Orig. (100). 

 Filtrates : No formaldehyde or formic acid could be detected. From the 

 1st to the 11th fraction the NaCl gradually increased from (23'9) to (83 - 3), 

 at 100 atmospheres filtration pressure. At this point the pressure was 

 removed and filtration resumed after an interval of eight hours. Six fractions 

 of 5 c.c. each were then removed, and gave values decreasing from (112-6) 

 to (93-7). 



Eesidual Fluid : Tested immediately after the last decompression con- 

 tained (134-9). 



Conclusions. — Formalised gelatine containing sodium chloride retains 

 sodium chloride from a solution, on filtration, to a greater extent than 

 ordinary gelatine. The decompression in this case also leads to the 

 immediately following filtrates having a higher concentration of salt than 

 the original fluid, but the effect is more marked than with ordinary gelatine. 

 The concentration of the residual fluid is also much greater than with 

 ordinary gelatine. 



Filtration of Megatherium Lysin Through Various Percentages of Gelatine. 



Megatherium lysin diffuses slowly compared with crystalloids in general,* 

 and is probably of semi-colloidal character. It seemed probable that a 

 substance of this type would be considerably more affected by a change in 

 the concentration of gelatine than a good filter-passer such as sodium 

 chloride. Hardy's (1899) work on gelatine pointed also to the possibility of 

 considerable change in the structure of the jelly at about 7 per cent, gelatine, 

 which might lead to markedly different degrees of permeability between 7 

 and 15 per cent gelatine filters. 



Method. — Filters containing 15, 11, 9 and 7 - 5 per cent, gelatine in 0*8 per 

 cent. NaCl were tested for tightness with 0-8 per cent. NaCl, of which 

 10 c.c. were pressed through in each case to ensure a concentration of NaCl 

 in the succeeding filtrates of about 0'8 per cent. The fluid examined was 

 the haemolytic filtrate from a broth culture of B. megatherium diluted with 

 •an equal volume of 0'8 per cent. NaCl. 



Filtration was carried through at a pressure of 100 atmospheres and a 

 temperature of 10° to 12° C. and the filtrate was 'collected in fractions of 

 about 4 c.c. 



Examination for Lysin. — Table I. 



Original Fluid. — The haemolytic index (see above) was (50). 



* Cf. Craw (IV, 1905). 



