84 THE VICTORIAN NATURALIST. 



green pigment chlorophyll, which is also present in the leaves, 

 &c., of all the higher groups of plants. This can be proved by 

 immersing some of them in absolute alcohol, when the Algae will 

 be bleached, and the spirit will become of a green colour, owing 

 to the solubility of the contained chlorophyll in the alcohol. In 

 one of the tubes exhibited this has been done, then oil has been 

 added, which in its turn has abstracted the chlorophyll from the 

 alcohol, leaving it of a yellow colour. 



There are, however, many plants in the phylum Thallophyta 

 which have no colour, as in some species of Fungi, and amongst 

 the Algse there are species which have colour, but no visible 

 chlorophyll green. These have a bluish pigment diffused through 

 their cells, and are known as the Cyanophyceae. There is a tube 

 amongst the exhibits showing this colour given off by some 

 Oscillaria in water. Thus the blue-green Algae more readily 

 contaminate water, giving both colour and a musty smell to it. 

 In other cases where chlorophyll is present it is masked by a 

 reddish pigment, and the plants of this nature are sometimes 

 grouped as the Rhodophyceae. They include the genus Batracho- 

 spermum, which are so called from their resemblance to frog- 

 spawn (batrachys, frog, and sperma, seed). 



Glancing at the reproduction we find that the Chlorophycese, 

 which are most numerous, have nucleated cells, and in many 

 cases the sexual method of reproduction may be observed ; but 

 the Cyanophyceae have no distinctly perceptible nucleus, though 

 some observers have somewhat doubtfully recorded the finding 

 of slight nucleoid appearances in the cells, and the reproduction 

 of these plants appears to be asexual. 



In unicellular forms, such as Protococcus viridis (which, by the 

 way, has lately fallen under suspicion with other unicellular 

 Algae as being merely a phase in the life of another and filamentous 

 genus), a simple division of the cell into two or four takes place, 

 and the bodies so produced become active gonidia, produce 

 cilia, and, on the rupture of the cell wall, escape as motile cells 

 and swim freely about. After a time each cell comes to rest, 

 loses its cilia, and puts on a firm cell wall, finally becoming like 

 the original cell. Almost the same process occurs in Hormiscia 

 zonata, a cell of which may resolve itself into an active ciliated 

 body, which, on escaping, swims actively for a time and comes to 

 rest. Then, losing the cilia, and attaching itself to some foreign 

 object by its smaller anterior, and lately ciliated end, it elongates 

 rapidly, and by transverse division becomes like the parent 

 plant. The bodies which escape, and independently develop in 

 this way, are called macrogonidia. But another cell in the 

 original filament may have divided into many smaller bodies 

 called microgonidia, the function of which is somewhat different 

 from that of the asexual form just described. These smaller 



