Further Observations with the Electron Microscope on Spermatozoids in the Brown Algae

Abstract

Observations are recorded for Ascophyllum, Pelvetia, Himanthalia, and Dictyota in addition to Fucus which has already been described in a previous paper. Fibrillar disintegration of cilia has been obtained in all except Pelvetia , in each case to give nine peripheral strands and a central pair. This corrects a previous error for the hind flagellum of Fucus . Some facts are given regarding the internal organs associated with the parts of the cilia inside the body in Himanthalia and Dictyota . A proboscis similar to that previously described for Fucus has been demohstrated in Ascophyllum and Pelvetia , but is absent from Himanthalia and Dictyota . Himanthalia differs from the other Fucoids in the relative lengths of front and hind flagella. Dictyota has only a single flagellum. In all, the front flagellum is a Flimmergeissel with two rows of hairs, which, in certain cases, notably Himanthalia ; have very long hair points. In Himanthalia there is a large spine near the distal end of the front flagellum borne on one fibril of the peripheral series. In Dictyota there is a row of smaller spines at the front end of the flagellum borne in a line between the two lateral rows of hairs. These spines in Dictyot can be used as evidence regarding the internal symmetry of the whole cilium which is summarized in a diagram.