466 SEMI-CENTENNIAL OF TORREY BOTANICAL CLUB 
terial preserved in formalin and in alcohol, by both of which their 
contents are turned to a reddish-amber color.* 
Both the red-pigmented and colorless cells respond to several 
of the usual tests for tannins, and their contents may be similar to 
those of certain idioblasts which occur in the diaphragms of the 
stem, both in Pontederia and in Piaropus. Olivet thought the 
substance in these idioblasts was probably a fatty oil, but Rotherti 
reports that although these cells are filled with a strongly refrac- 
tive, ordinarily red-brown substance, yet in autumn the substance 
may be colorless, and can then be determined by the customary 
reactions to be tannin. I have also found these stem idioblasts 
to be colorless in plants of Piaropus azureus and Pontederia mon- 
levideensis growing in the conservatory in mid-winter, when they 
likewise seem to give the tannin reactions. Nevertheless, these 
microchemical tests for tannins, unsatisfactory at best, are so 
complicated by possible mixtures of other substances that we feel 
they are merely suggestive here. The large cells of the perianth, 
described above for the first time so far as I can find, appear to 
resemble the subepidermal idioblasts in the petals of Fumaria 
officinalis discovered by Zopf§ and at first described by him as 
* In writing this report on the pigment-containing cells, and on other peculiar 
cells which have been tested with reagents, I have depended somewhat, for checking 
p observations on preserved material, on plants of Pontederia montevideensis Hort. 
nsus in the conservatory of the New York Botanical Garden, which furnished the 
only шше fresh flowers; comparative studies, however, indicate that all the 
structures in question are so similar in the two species as to leave no room for doubt 
of the алайда of these statements to P. cordata. The plants of P. montevideensis . 
came from Cambridge, England, in 1901, and have been propagated vegetatively: 
the origin of the species appears to be unknown, and its botanical characters are un- 
described, according to Bailey. In vegetative habit it closely resembles the narrow- 
leaved forms often distinguished as P. cordata lancifolia (Muhl.) Morong, but I am 
confident it is distinct from that. Rothert (Bot. Zeit. 58: 96. 1900) probably had 
Gard: j 
spelling montevideensis has been adopted from Index Kewensis Suppl. 4: 188. 1913, 
and is in harmony with the French practise in forming the name of the inhabitants 
of Montevideo, though montevidensis is said to be more in accord with Latin usage. 
fOlive, E. W. Contributions to the histology of the Pontederiaceae. Bot. 
Gaz. 19: 183. pl. 17. | 5, 6. 1894. 
f Rothert, W. Die Krystallzellen der Pontederiaceen. Bot. Zeit. 58: 78. 1900. 
$ Zopf, W. Ueber die Gerbstoff- und Anthocyanbehilter der Fumariaceen. 
Bibl. Bot. 1*: 20. 1886. For more literature on this subject see Solereder's Syst. 
Anat. of Dicotyledons (Eng. Ed.) 1: 57. 1008. 
