102 
INTERCELLULAR RELATIONS OF PROTOPLASTS. 
threads permeating the sieve plate, and connecting together 
the protoplasmic body of the constituent cells of the sieve 
tube.* * * § 
Several investigators have since turned their attention to 
the same deeply interesting point of structure, amongst whom 
Dippel f first demonstrated the presence of similar anatomical 
features in Vascular Cryptogams, and enriched science with a 
series of most carefully drawn figures from different plants; 
while RussowJ gave details of the forms of the tubes in 
different plants of the same groups, distinguishing, with 
Dippel, two main forms to which lie gave the names of 
Siebrohren (sieve tubes) and Siebgefasse (sieve vessels). By 
far the most important researches up to their date were, 
however, those of de Bary,§ published in his great work on 
the comparative anatomy of the vascular plants, to whom is 
due the merit of first drawing systematic attention to the 
contents of the tubes, although Briosi || had previously 
pointed out the very frequent presence of starch in the tubes, 
and had declared that he had by pressure forced the grains 
through the pores of the sieve plate. De Bary also first 
showed, in the case of the vine (Vitis vinifera), the absence of 
the sieve perforation during the winter months. 
Within the last two or three years the study of sieve 
tubes has entered into a new phase, and they have formed 
the subject of several excellent monographs, in which they 
have been dealt with mainly from a developmental point of 
* For further early literature :— 
Th. Hartig, ‘‘Die Entwickelung des Jalirringes.” Bot. Zeit., 1853, 
p. 571, ffalready referred to. 
Franck, “ Eiu Beitrag zur Kenntniss der G-efassbundel.” Bot. 
Zeit., 1854, p. 159. 
Schacht, “Der Baum.” 3rd Aufl., 1860. Schacht distinguishes 
here three types of sieve tubes in Phanerogams ; (1) Tubes transversely 
divided by simple sieves; (2) Tubes terminated by oblique partitions 
and provided with several sieves; (3) Fusiform tubes having sieves 
also on their radial walls. See pp. 208—15. 
f Dippel, Bericht der 39. Naturforscherversammlung zu Giessen, 
1884. See also “Das Mikroskop,” II. Theil, pp. 132, 199, 200, and 
Figs. 54 and 150 to 155. 
f Bussow, “ Vergl. Unters. ub. Leitbundel-Kryptogamen, 1872, 
p. 118, ff. 
§ De Bary, “ Yergl. Anatomie der Phanerogamen und Earne,” 
1877, pp. 179-191, and many figures. 
|] Briosi, “ Sopra la Generale Prezenza d’Amido nei Yasi Crivel- 
lati.” Nuovo Giornale Botanico Italiano, Vol. vii. (1875), pp. 83-108, 
and plate. 
