Vegetable Physiology for the Year 1836. 441 



the gap originates between the partitions of contiguous cells, 

 and indeed from a local separation of the membranes, and the 

 real dots , here showing themselves as the small and interior 

 circles, which consist of a cavity on the interior partition of the 

 cellular membrane raised towards the inner side. 



Valentin himself confesses that the porous opening exhibits 

 quite different forms, not only in different plants, but also at 

 times in various parts of the same plant ; but nevertheless he 

 considers it necessary to give various denominations to the 

 different parts. Thus he calls the space which characterises 

 the formation of the gaps, and which is continued in the true 

 porous opening, the gap-funnel; yet in the Conifer (B^ in which 

 Valentin has figured this gap-funnel so very great and so 

 plainly, this space is not present. The opposite end through 

 which the termination of the porous opening enters the cavity of 

 the cell, he calls the entrance-funnel^ and the more cylindrical 

 part situated between these, the middle part. 



He afterwards draws attention to the various forms of these 

 individual parts of the dots in various plants. I have 

 however not been able to find these forms so constant as 

 they are described. At all events it is highly gratifying that 

 Valentin has entered so minutely into details on this point; 

 there is much yet to be observed with regard to this, especially 

 in the dots of the spiral tubes. Valentin has also confirmed 

 the fact that the position of the dots on the sides of the 

 cells is a spiral one, a circumstance evidently connected, as I 

 have previously shown, with the formation of the cellular 

 membrane from spiral fibres; as the dots always occur 

 between the convolutions of those fibres running in a spiral 

 direction. The dotted ducts do not, according to Valen- 

 tin, stand perpendicular on the external layer of the cellular 

 partition (which is called the primary sac partition) but in a 

 rather slanting direction from the interior to the exterior, to- 

 wards the cellular partition. 



Dr. Hope * read on the 21st of March 1836, a paper on 

 the colours of plants, before the Royal Society of Edinburgh, 

 which in its results bears the greatest similarity to the beauti- 

 ful labours of Marquart which had appeared from eight to 

 nine months previously. Hope in like manner shows that 

 two different colouring matters occur in plants, one of which 

 forms with acids the red colours and is called on that account 

 Erythrogene^ while the other gives with alkalis the yellow com- 

 binations of colours and is named Xanthogene. These two 

 substances evidently represent the Anthohyan and Anthoxanthin 



* L'lmtitut, Feb. 15, 1837- 

 Third Series. Vol. 11. No. 69. Nov. 1837. 3 L 



