ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
71 
a long and extremely slender cilium. As soon as the motion ceases the 
zoospore rounds itself off, and begins to germinate. 
Botrydiopsis may also multiply vegetatively by repeated divisions ; 
and the resulting cells may either become transformed directly into 
zoosporanges, or may go thr<mgh a period of rest in tlie form of 
hypnosporanges invested by a thick membrane, the contents of which 
subsequently divide into zoogametes ; these are biciliated, without a 
pigment-spot or pyreuoids, and conjugate in groups of 2, 3, 4, or rarely 
a larger number. The zygosperms thus formed are perfectly spherical, 
with a diameter of 10-15 jx. After a period of rest, they develope into 
individuals precisely resembling those from which the series started. 
Signor Borzi considers Botrydiopsis as most nearly allied to Botry- 
dium, but as approaching the typical Confervaceae through Bumilleria 
(^HormotJieca). He pro})oses to divide the Confervales into 3 families, 
viz. : — (1) SciADEACE^ (^Characiopsis n. gen., Gharacii sp. auct., Peroniella, 
Chlorotheceium, Mischococcus, and Sciadium, including Ophiocytiiim) ; 
(2) CoNFERVACE^ (Confevva, Dictyotliele) ; (3) Botrydiace^ (^Bumilleria, 
Botrydiopsis, and Botrydium). 
Boodlea.* — Mr. G. Murray describes this new genus of Siphono- 
cladaceae, with the following diagnosis : — Alga viridis, marina, spongiosa, 
aspectu frondis defecta, ex filis confervoideis regulariter articulatis, 
iterum atque iterum ramosis, quocumque vergentibus, inter se per 
tenacula adhaerentibus composita. The only species, B. coacta, is from 
Japan. 
The author regards the genus as forming a very important link in 
establishing a connection between the Siphoneae and tbe jointed green 
algae. The individual filaments closely resemble those of Cladophora ; 
but instead of forming one plane, as in Microdictyon, they run in all 
directions, and are united by apical tenacles into a body which, when 
sw'ollen with water, has a pulpy spongy texture, and is net-like in 
whatever section it may be viewed. The apical tenacles adhere to any 
portion of the adjoining filaments with which they may come in contact. 
Dr. G. B. de Toni t refers to this genus several species hitherto 
included under Microdictyon. 
Volvox.J — Mr. E. Overton has made a careful study of the structure 
and development of this genus, especially of F*. minor. His results 
agree to a large extent with those of Klein. § He is disposed to regard 
the organism as an individual rather than as a colony. The colouring- 
matter of the red pigment-spot he finds to present similar chemical and 
optical properties to that of the fruit of Solanum. He confirms recent 
observations that the globe is filled, not wdth water, but with a 
mucilaginous substance. The parthenospores are found only in the 
posterior hemisphere. In V. glohator the number of these is almost 
invariably eight, while in V. minor it varies between one and eleven. 
The number of antherozoid-plates varies in direct proportion to that of 
the parthenospores or ovum-cells. 
* Journ. Linn. Soc. (Bot.), xxv. (1889) pp. 243-5 (1 pL). 
t Malpighin, iii. (1889) pp. 14-7. 
X Bot. Centralhl., xxxix. (1889) pp. 65-72, 113-8, 1-15-50, 177-82, 209-14, 241-6, 
273-9 (4 pis.). § Cf. this Journal, 1889, jt. 558. 
