ZOOLOGY AND BOTANY, MICROSCOPY. ETC. 675 



body with a very slender tail-like appendage, the rt mains of the proto- 

 plasm of the narrow stalk-like portion of the chib-shapi d antherid. The 

 body of the pollinoid is inclosed in a very thin membrane which does 

 not include the tail. 



Autherozoids of Fucaceae.* — M. L. Guignard has investigated the 

 mode of development of the antherozoids of several species of Fucus, 

 Peh-etia, Halldnjs, and Cystosira, which he finds to agree in all essential 

 jiarticulars ; Fucus scrratus may be taken as a tyj^e. Each antherid gives 

 birth to sixty-four antherozoids; tlie nucleus of the antherid divides 

 first of all, by repeated karyokinetic bipartition, into sixty-four nuclei, 

 distributed uniformly through the protoplasm. la forming the anthero- 

 zoids, the protoplasm divides and collects round the nuclei ; and to each 

 nucleus is attached a chromatophore, at first uncoloured, which becomes 

 subsequently the coloured so-called " pigment-spot." The two cilia of the 

 autherozoid are formed from a delicate peripheral protoplasm-ring. The 

 anterior cilium is fixed, for a portion of its length, to the body of the 

 autherozoid, and serves, when in motion, as an oar ; the posterior cilium 

 is inserted at the point of contact of the " pigment-spot " with the proto- 

 plasm, is twice as long as the anterior cilium, and serves as a rudder. 

 The mature autherozoid is pyriform, and is, in its origin, a naked cell 

 provided with two cilia and with a " pigment-spot " ; and differs there 

 fore in its homology from that of the Characeasl and other higher Crypto- 

 gams, which is derived from the nucleus only of the mother-cell. 



Ectocarpuf.| — M. E. Bornet adopts Kjellman's distribution of the 

 species of Ertocarpiis among three genera, — Isthmoplea, in which the 

 unilocular sjDoranges are partially buried in the frond ; Ectocarpus, in 

 which they are entirely external ; and PylaieUa, in which they are 

 intercalary, in a long tudinal row To the last section belong F. 

 fulvesrens, Hooperi, and nanus ; and he now gives a detailud description 

 of Ptjlaiella fulvescens. The only known mode of propagation is by 

 zoospores contained in unilocular zoosporanges. These are the lai'gest 

 known among the Pha^osporeae, measuring 13—17 /x in thickness, and 

 80-35 /x in length, resembling those of Cutleria multifida. They have 

 two unequal vibratile cilia ; the longer one, pointing forwards, does not 

 exceed the length of the zoospore ; they germinate wjthout cnnjugation. 

 The species is also remarkable from the protoplasmic cell-contents 

 being arranged in stars, resembling the appearance in Zygnema except 

 in colour'. 



Desmarestia aculeata.§ — Herr E. Soderstrom gives a careful 

 description of the anatomical structure of this seaweed. The stem 

 springs from the base of the true thallus or attachment-disc, and 

 branches regularly. The so-called " thorns " are the result of the arrest 

 of growth of certain lateral branches, and afterwards fixll off. Some of 

 the branches are clothed with very delicate silky hairs, which result 

 simply from vei-y fine branching of the thallus, and contain abundance 

 of chlorophyll ; they also are deciduous, and must be regarded as organs 

 of assimilation. Besides these lateral hairs, the young branches also 



* Coraptes Kenclus, cviii. (1889) pp. 577-9; and Kev. Gen. de Bot. (Bonnier), i. 

 (1889) pp. 137-45 (1 pi.)- 



t Ct". tirs Joum il, ante, p. 417. 



+ Rev. Ge'i. do Bot. 'Bouiiier), i. (1889) pp. 1-10 (1 pi). 



§ Bill. Svcusk. Vot.-Ak,id. Haudl., xiv., Afd. iii. (ISSJ) No. 3 (10 pp and 1 pi.). 



