CONTINUITY OF PEOTOl?LASM IN CELLS. 217 



the protrusions at the bordered pits there extend extremely deli- 

 cate threads of protoplasm which have a granular character. 

 The threads are somewhat curved (especially the outer ones), 

 and are slightly swollen in the middle. In peculiarly good 

 preparations it has been shown that there is an apparent inter- 

 ruption at the middle of their course, but that at this break 

 there are still minute filaments which serve to connect them. 

 From these and kindred observations Strasburger and some 

 others have adopted the view that there is such a degree of 

 continuity between the protoplasmic masses in the cells that 

 the}' form throughout the plant an unbroken whole. 1 



592. That protoplasm ma}' perhaps occur in intercellular spaces 

 appears from the observations of Russow 2 and of Berthold. 3 To 

 demonstrate this, one-year-old twigs of Ligustrum vulgare are 

 hardened for a few days in absolute alcohol, longitudinal sections 

 of the primary cortex placed in dilute iodine solution (see 30), 

 the excess of iodine removed, and dilute sulphuric acid added. 

 The contents of the cells and of the intercellular spaces will then 

 appear as yellowish-brown masses. 



593. That protoplasm can in some cases pass through an im- 

 perforate cell- wall appears from the observation of Cornu, 4 that 

 in the formation of the macroconidia of a certain Nectria all the 

 protoplasm of the five or six cells of the spore emerges to form 

 the macroconidium, which arises as an outgrowth of one of the 

 cells of the spore. The four or five partition- walls through which 

 the protoplasm must pass are, however, neither dissolved nor 

 perforated. 



It is probable that a striking phenomenon of fertilization in 

 phrenoganis, namely, the complete emptying of the pollen-tube 

 of its protoplasm (see "-Fertilization") without apparent break 

 in the continuity of the wall, must be referred to the same pene- 

 trative power of protoplasm. 



The withdrawal of the principal part of the protoplasmic 

 matters from deciduous leaves before the fall of the leaf may be 

 perhaps explained in the same way. 



Strasburger cites as an illustration of this penetrative power 

 the well-known case of the removal of protoplasmic matters 



1 Das botanische Practicum, 1884, p. 617. Strasburger : Bau und Wachs- 

 thum der Zellhaiite, 1882, p. 246. Frommann : Beobaclitungen iiber Structur 

 des Protoplasnia der Pflanzenzellen, 1880. 



2 Sitz. der Dorpater Xaturforscher-Gesellschaft, 1882, p. 19. 



3 Berichte der deutscheii botanischen Gesellschaft, ii. 20. 

 v ^omptes Rendus, 1877, tome Ixxxiv. p. 133. 



