As no specialist in Algology has replied to the inquiry of your correspondent â D. R.,â in NATURE for January 15, I maybe permitted to quote for his information the following from the article â Nucleus,â in the â Treasury of Botany â from the pen of the author of the â Introduction to Cryptogamic Botanyâ :â â In Algæ the term is applied to the fructifying mass of the Rhodosperms, whether contained in a single cell or in a compound cyst or conceptacle, the word nucleoli being used when there is a group of nuclei.â The instance alluded to by your correspondent is, unfortunately, not the only one in which the terminology of cryptogams is in a state of most perplexing confusion.