50 THE PLANT WORLD. 



longer portion springs out straight simulating a branch. In Scy- 

 tonema, a form closely allied to this, twin branches are formed by the 

 breaking of the bow near the middle and the two branches protruding 

 throuo^h the rent continue orowins; in lenoth. 



The Gloiotrichia colonies (fig. 5) are brownish-green balls, not firm 

 like Xostoc, but feathery or hairy. Magnified, these balls resolve 

 themselves into hundreds of whip-like objects embedded in jelly, radi- 

 ately disposed, the handles coming together at the center and the lashes 

 curled around at the periphery of the ball. A heterocyst adheres to 

 the end of the whip handle. The cell next to this grows long, resem- 

 bling the handle of the whip, but the remainder of the filament de- 

 creases in size until it ends in a mere hair. The long, thick-walled 

 cylindrical cell (the whip handle) is a spore and after the remainder of 

 the filament falls off this spore after resting develops into a new plant, 



In Gloiotrichia as in both Nostoc and Tolypothrix we find hormo- 

 gones which form new colonies and also, as in Nostoc, no definite grow- 

 ing point. But it is an improvment on Nostoc in that it has an apex 

 and base. Like Tolypothrix and Scytonema it forms false branches. 



The name Gloiotrichia is descriptive, hinting of the gelatinous sheath 

 and the hair-like end of the filament. Greek gloia, glue, and trich, a 

 hair. 



Of the green algae two representatives were abundant, Spirogyra 

 and Micrasterias. These both belong to the order Conjugatae. , 



Spirogyra [figs. 6, 7, 8,] is too well known to need a general de- 

 scription here, but this particular form was interesting because it 

 showed the cell contents more distinctly than is common. Just inside 

 the cell wall the peculiar ribbon-shaped, spiral chlorophyll bands were 

 coiled. The nucleus, an ellipsoidal translucent body in the center of 

 the cell, could be seen without staining. The starch-forming bodies, 

 pyrenoids, embeded in the chlorophyll band, w^ere large. After 

 staining, the protoplasmic threads attached to the back of these bodies, 

 by which the nucleus is suspended in the center of the cell, could be 

 seen. 



Spirogyra material can be readily stained in the following way. 

 Place the filaments in 1 per cent chromic acid and leave about twenty- 

 four hours. Then wash for twenty-four hours by changing the ma- 

 terial several several times into fresh or distilled water. It should 

 then be placed directly in Beale's Ammonia carmine (sent out ready 

 for use by Bausch & Lomb), and left for twenty-four hours. If 



