( 705 ) 
myself 1 ), the growth of cells without nuclei is very slight and 
gradually stops completely. In anuclear cells with chromatophores 
and in those without chromatophores, the two kinds being obtained 
by centrifuging the cells before or during karyokinesis, the tannin 
content after a time becomes very considerable, as shown by exami¬ 
nation with caffeine- and antipyrine solutions. In the absence of a 
nucleus growth stops, and as a result the consumption of tannin 
must have fallen off or has stopped altogether. Its production is 
however continued for some time; hence the increase of the tannin 
content in cells without nucleus. In this case also there is cessation 
of growth and an increase in the tannin content. 
The results obtained with non-growing nucleated and with non- 
nucleated cells, agree with those which I obtained with cells con¬ 
jugating and undergoing division, but are of less importance for the 
explanation of the physiological significance of tannin, because non¬ 
growing nucleated cells must be considered diseased, and those 
without nuclei are very abnormal. The results obtained with con¬ 
jugating cells and with cells undergoing division, I consider on the 
other hand of great importance for the explanation of the physio¬ 
logical meaning of tannin, which in my opinion must be regarded 
in Spirogyra as a substance which serves in the formation of the 
cell walls. The tannin is here not a reserve-material, however; it 
belongs to the soluble substances which the plant continually requires 
for its development. It disappears and gives way to reserve-materials, 
when the plant forms zygospores and passes into the resting condition. 
Hence I have arrived at a result, which agrees with the conclusions 
published by Wigand nearly half a century ago, but which militates 
against the view of later investigators, such as Sachs, Kraus and 
others. For the sake of clearness I must add, that I do not at all 
claim that tannin is the only substance, which is used in the formation 
of the cell wall of Spirogyra , nor do 1 wish to argue that the only 
physiological significance of tannin is its use as a plastic material. 
This paper is a preliminary one. It is my intention to report at 
some future time more fully on the physiological significance of 
tannin in Spirogyra, and to illustrate with tables the conclusions 
relating to the comparative experiments on the growth of Spirogyra 
filaments under various conditions, i. e. in antipyrine- and caffeine 
solutions, in ditch water etc. At the same time various points of 
investigation, relating to the tannin problem, and not mentioned in 
this paper, will be dealt with. 
1) c. VAN Wisselingh, Over wandvorming bij kernlooze cellen. Reprint from 
Bot. Jaarb. Dodonaea, Vol. 18, 1904, p. 5 and 6. Zur Physiologie der Spiro- 
gyrazelle, Beihefte zum Botan. Centralblatt, Bd. XXIV, Abt. 1, p. 170. 
