Stopes and Fujii. The nutritive relations of the surrounding tissues etc. 15 
By staining alone it is extremely diflicult to recognise the 
final closing lamella. As well as several otlier stains, Congored 
shows np the “sieve structure” very well, but chlorzinciodine owing 
to its deep staining property is the best. With this type of stain 
however it appears as thongh the pores of the sieve themselves 
represent the final open Communications, which is due to the 
fact that the final closing membrane does not stain with cellulose 
stains. That there is such a difficulty in the staining of the pit 
closing membrane was already noticed byBussoAv 1 ) and Gardiner 2 ). 
According to Mangin 3 ) the final pit closing membrane, which is 
the middle lamella, consists of pectin substance and is to be stained 
by a different series of staining substances than those used for cellulose. 
Among them ruthenium red 4 * ) is the most characteristic. We found 
however that even with the latter the final membrane is not very 
clearly demonstratable here owing to its extreme thinness, and 
consequently the small amount of stain it can take up. The tliick 
part of the egg membrane stained very darkly, and then the 
“secondary*’ and “tertiary” thickenings on the wall of the “sieve“ 
portion get gradually less and less dark tili one can scarcely see 
the membrane across the final sieve pores (cf. hg. 3). 
By swelling the lamella however, we were able to demonstrate 
its existence, as well as the fact that it is perforated by extremely 
fine pores, to see the actual plasmic connections, and also to 
determine the fact that the only actual plasmic Communications 
between the cells are “plasmodesmen’*. The best material for the 
demonstration of these finest of threads we found to be Encephalartos 
Lelimanni , of which we used hand sections of alcohol material. These 
sections were washed in water, treated for a short time with H 2 S0 4 
and then deeply stained with aniline blue. In spite of the fact 
that it is very simple, this method gave very satisfactory results. 
The membranes were muck swollen, and when examined with 
an oil immersion of strong magnification the sieve pores were seen 
to be closed by a very delicate lamella pierced by plasmodesmen 
in groups of 3 or 4 together (see fig. 1 and 2). Not only the 
middle lamella which constitutes the closing membrane of the finest 
sieve pores, but also the thicker portions of the closing membrane 
for the pits of l st Order, 2 nd Order and so on, we found to be 
traversed by the plasmodesmen. Thus plasmodesmen may be said 
4 ) Russow, E. A. E., „Ueb. Tüpfelbildung u. Inhalt d. Bastparenckym- 
u. Baststraklzellen d. Dicot. u. Gymnosp.“ (Sitzungsber. d. Raturforscker- 
Gesellschaft. Dorpat 1882. p. 350—389.) 
2 ) Gardiner, W., ,.On the continuity of the protoplasm through the 
walls of veg. cells“. (Phil. Trans. Boy. Soc. Lond. 1883. p. 827.) 
3 ) Mangin, L., „Sur la Constitution d. 1. membrane d. vegetaux“. (Compt. 
Bend. Vol. 107. 1888. p. 144 to 146.) „Sur la presence d. composes pectiques 
d. 1. vegetaux“. (Compt. Bend. Yol. 109. 1889. p. 579—582.) „Sur la substance 
intercellulaire“. (Compt. Bend. Yol. 110. fig. 90. p. 295.) Sur les reactifs 
colorants d. substances fondamentales d. 1. membrane. (C. B. Yol. 111. 1890. p. 120.) 
4 ) M angin. L.. „Sur l'emploi d. rouge d. ruthenium en anatomie vegetaleY 
(Compt. Bend. V 7 ol. 116. 1893. p. 653.) 
