10 



nuclear dyes, rarticulr.rl:' with Heidenhain's haematoxyiin. 

 Cytoplasmic stains, such as eosin, color them much less 

 intensely. They are soluhle in Javelle watei-, as was 

 pointed out by Kienitz-GEKLOFP ('02). This fact, coupled 

 with the fact that the disks exe continuous on both sides 

 Y/ith unaltered cytoplasm, gives support to the view, first 

 ej:pressed by SCHIvIITZ (*83) tlmt they axe protoplasmic in 

 nature. 



The results obtained by vexious workers on intercel- 

 lulair connections in the red algae are conflicting, ARCHER 

 (»80) described in Ballia.. pits which are at first open 

 and later become closed by a plug, or "stopper". SCHLUTz 

 (•83) came to the conclusion that the pit is closed by a 

 delicate meinbrane, which is pierced by ma,ny or several 

 protoplasmic stra,nds, HICK (*84 , a,b) thought he had dem- 

 onstrated a simple protoplasmic strand passing tlirough the 

 open pit, MOORE (*85) found that a pit-closing membrane 

 is pierced by one or several protopleismic strands. WILLE 

 ( »86) described and figured a sort of sieve tube in Cysto - 

 cloniuin . HARVEY-GIBSON (»91) fo\md that in Polysip}ionia 

 fastigia ta an actual jjrotoi'lasmic connection is present 

 only in young stages and that later a plug closes the pore- 

 canal. However, he mentions that from the edges of tlie 

 plug fibrillsr thickenings connect the neighboring proto- 



