Current Literature . 
9 
islands ” of sclerenchyma and phloem first described by Poirault in 
1893, cannot be discussed here, but it may be said that they con¬ 
tribute in an important degree to the general theory of the evolution 
of the vascular system of Ferns which we shall very soon be in a 
position to formulate. 
Starch-Formation in Hydrodictyon. 
Mr. Timberlake of Wisconsin University contributes to the 
same periodical an important paper on Starch-Formation in 
Hydrodictyon. 
Mr. Timberlake finds in the first place that the whole of the 
cytoplasm, with the exception of the ectoplasm and vacuole-wall, 
contains chlorophyll, so that in Hydrodictyon there is no specially 
differentiated chromatophore. 
By the application of modern cytological technique he has 
succeeded in shewing that the distinction drawn by Klebs between 
pyrenoid-starch (formed immediately around the pyrenoids) and 
stroma-starch (formed in the substance of the chromatophore 
without relation to the pyrenoids) is illusory, and that the whole of 
the starch found in the Hydrodictyon -cell is derived from the 
pyrenoids. Actual pieces of these are cut off, changed into starch, 
and pushed out into the surrounding cytoplasm, where their 
arrangement and shape often clearly indicate their origin. The 
author is of opinion that the pyrenoid is “ an active body, 
differentiated in the chlorophyll-bearing cytoplasm, which in co¬ 
operation with the latter acts as the base of the process of starch- 
formation.” How far these conclusions can be extended to all 
algal cells possessing pyrenoids, and what is the significance of the 
apparently fundamental difference between this method of starch 
formation and that obtaining in the plastids of the higher plants, 
must remain at present open questions. 
[We hope to make the “ Notes on Current Literature” much 
more extensive in succeeding numbers.] 
