V] OF BEADS OR GLOBULES 387 



repeated on a grosser scale when the web is bespangled with dew, 

 and its threads bestrung with pearls innumerable. To the older 

 naturalists, these regularly arranged and beautifully formed globules 

 on the spider's -web were a frequent source of wonderment. Black- 

 wall, counting some twenty globules in a tenth of an inch, calculated 

 that a large garden-spider's web should comprise about 120,000 

 globules; the net was spun and finished in about forty minutes, 

 and Blackwall was filled with admiration of the skill and quickness 

 with which the spider manufactured these little beads. And no 

 wonder, for according to the above estimate they had to be made 

 at the rate of about 50 per second*. 



Here we see exemphfied what Plateau told us of the law of minimal 

 areas transforming the cylinder into the unduloid and disrupting it 



Fig. 114. Root-hair of Trianea, in glycerine. After Berthold. 



into spheres. The httle dehcate beads which stud, the long thin 

 pseudopodia.o.f a foraminifer, such as Gromia, or which appear in 

 like manner on the film of protoplasm coating the long radiating 

 spicules of Globigerina, represent an identical phenomenon. Indeed 

 we may study in a protoplasmic filament the whole process of 

 formation of such beads: if we squeeze out on a shde the viscid 

 contents of a mistletoe-berry, the long sticky threads into which the 

 substance runs shew the whole phenomenon particularly well. True, 

 many long cylindrical cells, such as are common in plants, shew no 

 sign of beading or disruption ; but here .the cell- walls are never fluid 

 but harden as they grow, and the protoplasm within is kept in place 

 and shape by its contact with the cell-wall. It was noticed many 

 years ago by Hofmeisterf, and afterwards explained by Berthold, 

 that if we dip the long root-hairs of certain water-plants, such as 

 Hydrocharis or Trianea, in a denser fluid (a httle sugar-solution or 



* J. Blackwall, Spiders of Great Britain (Ray Society), 1859, p. 10; Trans. Linn. 

 Soc. XVI, p. 477, 1833. On the strength and elasticity of the spider's web, see 

 J. R. Benton, Amer. Journ. Science, xxiv, pp. 75-78, 1907. 



t Lehrbuch von der Pflanzenzelley p. 71 ; cf. Nageli, Pflanzenphysiologische Unter- 

 suchungen [Spirogyra), ni, p. 10. 



