PLATE V.— CONFERVACE.E, ULVACE^, and MYXOMYCETES. 



( 'Reproduction and Development principally after Oersted.) 



Confervaceje (Lat confervere, to unite) are filamentous Algae, occurring plentifully in every stagnant water, usually in great abun- 

 dance round the margin. The filaments grow in length by the individual cells dividing into two Multiplication takes place by 

 Zoogonidia, and Conjugation has been observed in Cladophora. 



Figs. 1 and 2. Cladophora (Gr. k/ados, a branch ; phono, I bear), so named from its being branched, is a very common form. 



Examine a small portion in water. 



Filament with alternate branches forming. The top of the cell puts forth a little pocket at one side, which 

 grows and divides like the parent filament Secondary branches may likewise be formed, thus giving rise to bushy 

 tufts. One or more nuclei may be present in each cell. 



Fig. 3. Treatment with Iodine, showing starch granules. 



The contents are seen to be broken up into little ovoid masses called chlorophyll-corpuscles, and it is in these 

 the starch is formed. 



Yellowish brown colour indicates protoplasm. 



The darker spots are in reality dark-blue, indicating their starchy nature. 



The cellulose wall is clearly differentiated from the contents. 



Fig. 4. Multiplication by Zoogonidia. 



The contents of the cells break up into little masses, which round themselves off, acquire cilia, and escape by a 

 break in the side of the wall. 



Fig. 5. Zoogonidia germinating. 



They lose their cilia, begin to elongate, and grow to a filament. 



Ulvace^e form flat expansions of cells, and are commonly met with on the seashore. The common green Laver (U. latissima) may 

 be a foot square, and is so puckered and folded that it seems branched. Enteromorpha may be regarded as a tubular Ulva; and as 

 Conjugation has been clearly observed in it, the process will be described in that connection. 



Fig. 6. Mount a small piece in water and examine. 



The cells are angular from pressure, and dark spots appear in each. 



Fig. 7. Highly magnified portion. 



A number of the cells contain Zoogonidia. The Zoogonidia escape by small openings on the surface, and 

 move about in the water by means of cilia. 



Enteromorpha (Gr. enteron, intestine ; morp/ie, shape), instead of being flat, like Ulva, forms a slender tube. It occurs plentifully 

 on the seashore, attached to stones, rocks, or even seaweed, and also forms those slimy, green growths so common on the posts of piers, 

 etc. In the autumn particularly the cells give rise to innumerable actively moving Zoospores. These come together in the water, and 

 Conjugation takes place. The result is a Zygospore, which is believed to germinate in the ensuing spring and become a new Entero- 

 morpha. 



Fig. 8. It consists of a tapering attached end, giving off numerous small branches, then expanding till it reaches the apex, where 

 a slender forked portion branches off a little to one side. The surface of this specimen is puckered, and here and 

 there delicate branches are formed. 



Figs. 9 and 10. Take a small portion and examine under microscope. 



The tube is seen to consist of a single layer of cells, and when spread out, as in Fig. 9, quite resembles the 

 frond of Ulva. 



Fig. 11. Portion highly magnified. 



Some of the cells are still in the vegetative condition, others are full of Zoospores, in some the contents have 

 escaped, and on the left side the Zoospores are seen in the act of escaping, enveloped by the inner membrane of 

 the cell. 



Figs. 12 and 13. Micro-'zoospores free and conjugating. 



Two Zoospores meet by their pointed ends, then swing round side by side, blend, lose their cilia, and become 

 a pear-shaped Zygospore. 



Life History of Conferracece and Ulvacece. — The cells either produce Zoogonidia, which grow into a new plant, or Zoospores, 

 which conjugate, thereby forming Zygospores to reproduce the plant. 



Myxomycetes (Gr. muxa, slime ; mukes> a fungus), or Slime-fungi, as their name denotes, are slimy bodies found on rotten wood, 

 decaying leaves, etc.; and the specimen chosen — Aethalium septicum, or "flowers of tan" — occurs on spent tan. It is of a creamy, 

 yellow colour; and in nurseries, where spent tan is used for bottom heat, it may be found in the autumn overspreading large surfaces, 

 and, forced by the heat, it has been known to make its way up the stems of plants. The limit of heat for this form is 40 C. 



The Myxomycetes are peculiar in passing through an Amoeboid stage, when they take in solid nutriment and feed like animals, so 

 that in this stage of their existence at least they resemble animals rather than plants. Their life history too is quite comparable to 

 that of some of the lower animals, as may be seen from the Figures. 



Fig. 14. Aethalium septicum (Gr. aithales, splendid, from its appearance). 



(a.) The Amoeboid stage, or Myxopod of the animal series, possesses a nucleus. 



(b.) The Plasmodium stage is the large, conspicuous, yellowish mass, made up of a protoplasmic network show- 

 ing streaming of the contents as indicated by the arrows. 



(c.) The Spore possesses a thick cell-wall, which bursts to allow the contents to escape. The rounded mass 

 developes two cilia, which become reduced to one, and thus a body is formed like the Mastigopod of 

 the animal series. Even this single cilium disappears, and the Amoeboid stage is reached, as at the 

 beginning. 



Fig. 15. Sporangium of Arcyria — unopened and opened. The elasticity of the fibres composing the Capillitium (Lat capillus, a 

 hair) ultimately ruptures the case and jerks out the spores. 



