26 Hydration and Growth. 



Still another type of inclusion was tested by the incorporation of 

 spores of Lycopodium in liquefied agar. These spores are not readily 

 wetted, and hence they could be worked into a colloidal mixture only 

 at low temperatures, when it was in a stage nearing gelation. 



The first attempt was one in which 2.5 parts by weight of spores were 

 mixed with 40 parts by dry weight of agar. The agar was liquefied in 

 the usual manner, and when it had come down to a temperature of 

 about 40 was strained through cheese cloth into a beaker. The quan- 

 tity of spores given above was now placed on the surface and the whole 

 was vigorously stirred for several minutes with an ordinary revolving 

 egg-beater. The agitation was continued until the temperature fell 

 to 35° C, when the whole was cast as a plate in the usual manner. The 

 dried plate was 0.3 mm. in thickness and showed the spores and 

 numerous clumps of spores embedded in it, with very few really coming 

 to the surface. "V^en sections of the ordinary size were cut and swelled 

 at 18° C. they showed some buckling. The swellings in distilled water 

 and in asparagin 0.05 M were equivalent, being 850 per cent in 24 hour?, 

 with some increase still in progress, the rate being greater in distilled 

 water. 



The second test was arranged with sections 0.27 and 0.28 mm. in 

 thickness, which swelled 1,125 per cent in 0.01 M asparagin and 667 

 per cent in acetic acid 0.01 N, both pairs of tests showing an expansion 

 far less than might be expected from the agar alone. It seems quite 

 safe to conclude that inclusions such as bodies of zein, globulin, coagu- 

 lated albumin, fine threads of glass, cotton fibers, and spores lessen the 

 hydration capacity of the gel in which they may be embedded. As 

 their effects are due directly to the area of surface and radius of curva- 

 ture, the action of a comparatively small amount of finely divided 

 material would be very much greater in the cell. The foregoing results 

 are in accordance with those of Hardy, who found that solids included 

 in a colloid before fixation may influence the structure of films in a 

 material manner. Grains of carmine incorporated in liquid colloids 

 modified the mesh and the thickness of the plates or bars or more sohd 

 material, and the prevalence of insoluble particles in plant cells renders 

 such observations of great interest.^ 



'Hardy, W.B. On the structure of cell protoplasm. Journal of Physiology, 24 : 158. 1899. See 

 p. 186. 



