INTERCELLULAR RELATIONS OF PROTOPLASTS. 
101 
ON THE INTERCELLULAR RELATIONS OF 
PROTOPLASTS.—II * * * § 
BY WILLIAM HILLHOUSE, B.A., F.L.S., 
PROFESSOR OF BOTANY AND VEGETABLE PHYSIOLOGY AT THE MASON SCIENCE 
COLLEGE, BIRMINGHAM. 
[Continued from page 66 .] 
Sieve Tubes. — The existence of open communication 
between certain cells of the higher plants, namely, between 
the different anatomical elements which compose sieve tubes, 
and between adjoining sieve tubes, has been for many years 
well known. Attention was first drawn to these structures 
as forming a constituent of the bast portion of the fibro-vasal 
bundle of at least the phanerogams by Tli. Hartig f in his 
great work on the native trees of Germany, and to them he 
gave the name of “ Siebfasern.” Little attention, however, 
appears to have been paid to these structures until after the 
publication by the same investigator many years later of a 
detailed account of this tissue in Cucurbita Pepo.\ The 
subject was then taken up by the distinguished morphologist, 
von Mohl,§ whose influence at that period preponderated in 
all branches of vegetable anatomy. Yon Molil first proved 
the existence of sieve tubes in Gymnosperms, denied by Hartig. 
Little actually new was, however, added until Nageli|| demon¬ 
strated that the sieve plates were actually perforated, a fact 
confirmed by Sachs I 1 and further by Hanstein,** by means 
of the now classical method of treatment by iodine and sul¬ 
phuric acid, showing clearly the existence of protoplasmic 
* Transactions of tlie Birmingham Natural History and Micro¬ 
scopical Society. Bead March 18th, 1884. 
+ Tli. Hartig, “Vergl. Untersuchungen iib. d. Organisation des 
Stammes d. einheimischen Waldbiiume,” 1837. 
X Th. Hartig, Bot. Zeit., 1854, pp. 51—4. The same author had 
previously referred to these structures in “ Yollst. Naturgescli. d. forstl. 
Culturpfl.,” Berlin, 1851, and Bot. Zeit., 1853, p. 571. 
§ Yon Mohl, “ Einige Andeutungen lib. d. Bau d. Bastes.” Bot. 
Zeit., 1855, p. 865, f.f. For proof of presence of sieve tubes in 
Gymnosperms, see p. 891. 
|| Niigeli, “Ueber d. Siebrohren.” Sitz. d. Bair. Akad., 1861,1., 
p. 212. 
Sachs, in “Flora,” 1863, p. 68. 
** Hanstein, “Hie Milclisaftgefiisse u. verw. Organe,” 1864, p.23, ff. 
