Elementary botany . g water, and in a dayor so the swarmers are likely to be found. Under certain conditions smallmicrozoids are formed. 336. Chlamydomonas is a very interesting genus of motile one-celledgreen algae, because the species are closely related to the Flagellates amongthe lower animals. The plant is oval, with a single chloroplast and sur-rounded by a gelatinous envelope through which the two cilia or flagellaextend. One-celled organisms of this kind are sometimes called monads,, a one-celled being. This one has a gelatinous cloak and is, therefore,a cloaked monad {Chlamydomona
Elementary botany . g water, and in a dayor so the swarmers are likely to be found. Under certain conditions smallmicrozoids are formed. 336. Chlamydomonas is a very interesting genus of motile one-celledgreen algae, because the species are closely related to the Flagellates amongthe lower animals. The plant is oval, with a single chloroplast and sur-rounded by a gelatinous envelope through which the two cilia or flagellaextend. One-celled organisms of this kind are sometimes called monads,, a one-celled being. This one has a gelatinous cloak and is, therefore,a cloaked monad {Chlamydomonas). The species often are found as a verythin green film on fresh water. C. pulvisculus is shown in fig. 163. Whenit multiplies the single cell divides into two, as shown in B. Sometimes anon-motile palmella stage is formed, as shown in C and D. Reproduction, i6o MORPHOLOGY. takes place by gametes which are of unequal size, the smaller one repre-senting the sperm and the larger one the egg, as in E and F. These con-. Fig. pulvisculus (Mull.) Ehrb. A, an old motile individual; n,nucleus; p, pyrenoid; s, red eye spot; v, contractile vacuole; B, motile indi-vidual has drawn in its cilia and divided into two; C, mother plant has drawnin its cilia and divided into four non-motile cells; D, pamella stage; E, femalegamete —egg; F, male gamete —sperm; G, early stage of conjugation; H, zygo-spore with conjugating tube and empty male cell attached. (After Wille.) jugate as in G and H, the protoplasm of the smaller one passing over intothe larger one, and a zygospore is thus formed. 337. Of those which form colonies, Pandorina morum is widely dis-tributed and not rare. It consists of a sphere formed of sixteen individuals enclosed in a thin gelatinous mem-brane. Each cell possesses two cilia(or flagella), which extend from thebroader end out through the envelop-ing membrane. By the movementof these flagella the colony goes roll-ing around in the water. When theplant
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