IV. 
On tlie continuity of tlie protoplasm throngli the walls 
of vegetable cells. 
By 
Walter Gardiner 
II. A., Scholar of Cläre College, Cambridge, and Demonstrator of Botany in the University. 
A most important addition to ourknowledge of the histologyof lissues 
was made in 1863 by Sachs 1 ) and in the following year by Hanstein' 2 ) when 
they dernonstrated that in the sieve-tubes first described by Hartig 3 ), there 
are perforations in the transverse partition walls, through which pass fila- 
nients of ])rotoplasm, and that thus there is continuity belween the proto- 
plasmic contents of adjacent cells. 
For a long time this discovery, aithough admirably confirmed and sup- 
ported by the researches of Wilhelm 4 ), Janczewski 5 6 ) and Russow 11 ), remained 
as an isolated fact until in 1880 Tangl 7 8 ) published cerlain results which 
afforded some practical proof of the correctness of the suggeslions as lo the 
existence of a closer connection between cell and cell which had beeil first 
made by Hofmeister s ) and subsequeully more thoroughly and emphatically 
enunciated by Sachs 9 ) and Strasburger 10 ), for Tangl succeeded in showing 
that in the ripe endosperm cells of Strychnos, Phoenix and Areen , eilher 
the general cell-wall, or the closing membranes of the pits were traversed 
by fine threads of protoplasm. 
1) Sachs. ‘Flora 1863’. p. 68. 
2) Hanstein. ‘Die Milchsaftgefäße’. Berlin 1S64. p. 23 et. seq. 
3) Hartig. ‘Bot. Zeit. 1854’. p. 51—54. 
4) Wilhelm. Beiträge z. Kenntniß &c. Leipzig 1880. 
5) Janczew'Ski. Etudes comparees sur les tubes cribreux. Cherbourg 1882. 
6) Russow. Sitzber. d. Dorpat. Nat. Gesell. 1882 . p 350 — 389 . 
7) Tangi.. Jahr. f. Aviss. Bot. XII p. 170—190. 
8) Hofmeister. See Sachs’ Vorlesungen, p. 102. 
9 ) Sachs. ‘Vorlesungen über Pflanzen-Physiologie’. p. 102. 
10 ) Strasburger. ‘Bau und Wachsthum’, p. 246. 
