548 



ORGANOLOGY. 



of the deposit-layers) become straight on drying, but again roll up on 

 being wetted, because the primary cell-membrane contracts in a dry and 

 expands in a moist condition. 



I have hitherto been able to make, respecting these facts, only a few 

 experiments, which, although they do not afford anything like correct 

 figures, for I will admit a probable error often per cent., yet, relatively 

 speaking, they have their value. The following are the results : 



Polyides lumbricalis, moderately thick-walled, gelatinous cells, and the 

 rather swollen extremity shortly before the formation of spores =A. 

 Laminaria diffitata, a piece of the ftsitfrons=B. Sphcerococcus crispus, 

 somewhat thicker cells of the frons=C. Sphcerococcus cartilagineus, 

 rather thick cells, a piece of the round peduncle of the frons=D. ; 

 measured in a dry state (all the measures are given in millimetres) =#, 

 after having been lying in the water for 3 hours=&, after 24 hours' 

 soaking in water =c, amount of the prolongation in decimals of the 

 original length =e?. 



E. Fibres of hemp (very elongated cells, thick- walled, the light dis- 

 appearing under the microscope, cellulose well developed) were sus- 

 pended in a glass tube, which was wider below, and enclosed in it for 

 24 hours with chloride of calcium, and then measured=a / . The chloride 

 was removed ; the end of the tube, which was open below, was immersed 

 in water, and measured after 24 hours =&'. The tube was then filled 

 with water, and again measured after the fibres had been 24 hours in 

 water=c'. During this process the temperature of the room fluctuated 

 between 10 and 18 R. Finally, the tube was emptied of its water, and 

 dried, with the fibres, over chloride of calcium at about 30 R., and again 

 measured =d'. The amount of the greatest elongation in decimals of 

 the original length gives e. The fibres 1 and 2 had at their end the 

 weight of a small shot, which was scarcely heavy enough to stretch them 

 straight ; the fibre 3 had upon it a rather heavier shot. 



E. \2. 

 1 3. 



a 



469 

 434 

 951 



b' 



470 

 434-5 



c 



470 



434-5 



594-1 



d' 



468-5 

 434 



e' 



0-0021 

 0-0011 

 0-0036. 



F. In the month of February a shoot of Salix alba of the previous 

 year was cut off and placed in water for 24 hours, at a'temperature of 

 10 to 15 R.; the bark was then taken off, and the length measured=a"; 

 it consisted entirely of alburnum, therefore of slightly thickened and 

 elongated cells with imperfectly developed cellulose : the small pith 

 may be here overlooked. The twig was now dried at a temperature of 

 10 to 15 R, and the length again measured=&" ; finally dried for 



