IV. On the continuity of thc protoplasm through llie walls of vegetable cells. 73 
is that of a flattened sphere, thc individual threads traversing the pit-inem- 
brane in a direction parallel to ihe long axis of the pit. The niost external 
threads on either side of the thread complex in passiug across the pit-inem- 
brane. hend out in a graceful eurve, reminding one of the meridian liues 
represented on a globe, exeept of course that they do not converge so as lo 
meet at a point as the meridian liues do at the north and south poles, hui 
ond bluntly at the intercepting free surfaces of the pit-closing-men'.brane. 
As one gradually approaehes an irnagjnary line joining the eenlres of the 
tvvo free surfaces of the pit-membrane, the eurve of the threads hecomes 
less and less, until immediately around tliis line, their direction hecomes 
praclieally straight. In an en face view of the pit one sees the ends of the 
threads as small stained poinls, dotted over the elosing membrane, and 
furthermore the well-dellned circle of the pit itself appears to he surrounded 
hy a less well defined and concentric circular area, \Vhich is the exprcssion 
of the bending outwards of the threads; the outline of this area marks the 
limits of the eurve of the rnost external of the threads; and in it, the separate 
threads of the thread-complex ean he ohserved curving upwards towards 
the free surface of the pit-closing-membrane. 
In unpitted cells in the samo way e. g. Tamm , Dioscorca and Strychnos 
the threads do not run in a perfeetly straight direction across thc thickness 
of the cell-wall, bul in each face of the wall , along whieh it is in contact 
Willi neighbouring cells, they become more curved the further they are 
from the central point of the face, in the very same way, as in the achro- 
matin fihres ohserved hy Stiusbuhger, in the nuclear di Vision attending free 
cell formation. Finally in certain instances, e.g. Bentinckia , Ilowea, Lodoi- 
cea, Kentia and Aspcnila hoth these means of communication are exempli- 
fied, for the pit-membranes and the general cell-walls too are traversed bv 
protoplasmie threads. In Hyophorbe , Idvistona and Wallichia the threads 
do not appear to eurve, but traverse the closing membrane, in almost 
straight lines. 
In Euterpe ( Areca) oleracea and Phoenix ductylifera, I was unable to 
find that the threads were well defined after treatment with Chlor. Zine. 
Jod., and Jodine, bul after staining with Picric Hoffmann’s blue, or after 
treatment with Sulphuric acid and Methyl violet they caine quite as clearly 
into View, as Taxgl represented in bis figures of them. 
In Ornithogalum also I was able to confirm Strasburger’s results, and 1 
have no douht that the same slructure would he equally well demonstrated 
in the cells of Taxodium distichum, and Viscum album. •) 
In Bomaria oligantha the closing membranes of the endosperm cells are 
somewhat thin, and the separate threads are hard to observe in longitudinal 
seetion but in an en face view of the pit the sieve-structure is clearly 
4) See. ‘Bau unil Waehsthum'. Tat. I. Fig. 4 7 am! Tat. II. Fig. 29. 
