44 MACDOUGAL— ACTION OF LIPOIDS IN GROWTH. 



the other main components of a lining layer in one series of prepara- 

 tions, but the effects of its action as minute globules distributed 

 throughout the mass were indeterminate, as noted above. A special 

 series prepared in such manner as to secure a lipoidal layer external 

 to the plasmatic mass and lying next to and in the wall was next 

 prepared. 



Clay filter thimbles which had been cleaned and warmed in dis- 

 tilled water were drained a few seconds, then 4 c.c. of a 2 per cent, 

 solution or emulsion of lecithin was poured into it. After stoppering 

 the thimble was turned in the hand for about two minutes in such 

 manner that the lecithin was made to bathe the entire inner surface 

 repeatedly. About 3 c.c. of liquid would be poured out when the 

 stopper was removed, but this would be of a lighter hue indicative 

 of the fact that some of the lipoid had been taken up by the cup, 

 where it would be held in the inner surface layer. If the properties 

 of the lecithin layer alone were to be tested, the osmometer head 

 would be put in, the desired solutions poured in through the funnel 

 tube, and the thimble set in the immersion fluid. If a more complete 

 simulation of the conditions in the cell were desired, the thimble 

 treated with lecithin received about 10 c.c. of liquid jelly, and after 

 being again stoppered was turned for another two minutes, when this 

 was also poured out, leaving a thin layer on the wall, and the osmom- 

 eter head put in place. Such cells now included a great central 

 vacuole to receive any desired cell-contents, had a plasma of an agar- 

 gelatine-soap mixture, and a peripheral layer of lipoid which had 

 undoubtedly penetrated the wall to some extent. The pores of the 

 clay walls were so large that solutions of potassium and sodium 

 would pass through them readily setting up no pressures. 



That the deposit of lecithin had effectually closed the larger pores 

 was evidenced by the fact that when cells treated with lecithin only 

 were filled with potassium chloride or sodium chloride at o.oiM, the 

 average endosmosis in 24 hours as measured by the excretion for 

 the potassium was 6 c.c. and slightly less than 4 c.c. for the sodium. 

 These figures represent the integration of the action of the two 

 kations on the lipoid and their osmotic pull. 



Next a series of cells with a lecithin layer and an inner layer of 

 agar and gelatine were arranged to test the influence of saponin on 



