Stopes and Fujii. The nutritive relations of the surrounding tissues etc. 15 



By staining alone it is extremely difticult to recognise the 

 final closing lamella. As well as several other stains, Congored 

 sbows up the "sieve structure" very well, but chlorzincioditie owing 

 to its deep staining property is the best. With this type of stain 

 however it appears as tbougb 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 difticulty in the staining of the pit 

 closing membrane was already noticed by Russow 1 ) and Gardiner 2 ). 

 According to Mangin 3 ) the final pit closing membrane, which is 

 the middle lamella, cousists of pectin substance and is to be stained 

 by a different series of staining substances than those used for cellnlose. 

 Among them ruthenium red 4 ) is the most characteristic. "We f'onnd 

 however that even with the latter the final membrane is not very 

 clearly demonstratable here owing to its extreme thinness, and 

 conseqnently the small amount of stain it can take up. The thick 

 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. fig. 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 linest of threads we found to be Encephalartos 

 Lehmann/', of which we used band 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 much 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 ,ul Order and so on, we found to be 

 traversed by the Plasmodesmen. Thus Plasmodesmen may be said 



*) Russow, E. A. F., „Ueb. Tüpfelbüdung u. Inhalt d. Bastparenehyrn- 

 u. Baststrahlzellen d. Dicot. u. Gvmnosp." (Sitzungsber. d. Naturforscher- 

 Gesellschaft. Dorpat 1882. p. 350—389.) 



2 ) Gardiner, \\\. ..Ou the continuitv of the protoplasm through the 

 walls of veg. cells". (Phil. Trans. Roy. Soe. Lond. 1883. p. 827.) 



s l AI an» in, L., ..Sur la Constitution d. 1. membrane d. vegetaux". (Compt. 

 Rend. Vol. 107. 1888. p. 144 to 146.) „Sur la presence d. composes pectiques 

 d. 1. vegetaux". (Compt. ßend. Vol. 109. 1889. p. 579-582.) „Sur la substance 

 intercellulaire". (Compt. Rend. Vol. 110. fig-. 90. p. 295.) Sur les reactifs 

 colorants d. substances fundamentales d. 1. membrane. (C R. Vol. 111. 1890. p. 120.) 



4 ) Mangin. L.. ..Sur l'emploi d. rouge d. ruthenium en anatomie vegetale". 

 (Compt. Rend. Vol. 11 6. 1893. p. 653.) 



