80 KEPORT — 1887. 



tents became homogeneous, and after keeping in sea-water for some days 

 showed no sign of lite. Berthold states that in Bancjia kept for several days 

 in absolute alcohol, and then brought into sea-water, many cells showed 

 the same appearance as in the living plant, while others were completely 

 killed and decolourised. I took great care in this experiment to avoid 

 diluting the alcohol by any moisture in the fibres, and my results were 

 curious. The fibres shrivelled up, cells contracted, and contents became 

 homogeneous, but the green colour remained, except at the torn end of a 

 fibre, where six or seven cells lost their chlorophyll, and showed the red 

 colour. Even when sjsecimens were kept in alcohol for a week, the green 

 colour remained in many cells ; sometimes cells towards the middle of a 

 fibre were decolourised, while those on both sides remained green. In no 

 case did the cells resume their normal appearance after being carefully 

 freed from alcohol by drying and returned to sea- water. 



In nature Bangia lives on the rocks above high-water mai'k, dashed 

 by the spray. This may explain the curious fact that I was able to keep 

 it alive in freshwater for eight days, while it died in four or five days 

 when kept in sea- water. In nature it is often exposed to heavy rain, 

 sometimes almost continuously for some days, and this probably accounts 

 for its resistance. I believe that if, instead of keeping the plant immersed 

 in water, it Avere simply kept moist by a spx'ay of fresh water, it would re- 

 main alive for a still longer time, though not so long as if moistened by a 

 spray of sea- water. Its quick death in sea- water I take to be due to its 

 immersion. 



The ordinai-y reagents used for killing — osmic acid, picric acid, subli- 

 mate, iodine — kiWedBangia very quickly, producing considerable changes 

 in its appearance. 



Porphyra leucostida showed similar phenomena, but its resistance is 

 considerably less than that of Bangia. It dies very quickly in fresh 

 water. 



The resistance of Bangia to reagents appears to be due mainly to the 

 cuticle which surrounds the fibi'es, which is insoluble in sulphuric 

 acid. Porphyra appears not to possess such a cuticle. Veiy young 

 plants of Porphyra, however, resisted glycerine for nearly an hour, 

 the cells gradually, from the base to the tip, becoming disorganised. 



The hypha-like prolongations of the basal cells of Bangia which form 

 the rhizoids, as a rule, pass down inside the tube to the base ; occasion- 

 ally, however, lateral roots are found ; and when this is the case the 

 rhizoid, surrounded by a thick membrane, pushes its way through the 

 cell wall and cuticle in a manner analogous to that of the roots of higher 

 plants. 



Bangiacece are not available in summer here ; in autumn and winter I 

 hope to do further work at them. 



I did a considerable amount of work on Acetahularia mediterranea, 

 following up its development from the state of a simple unbranched thallus 

 to the final development of the pileus. The memoirs of De Bary and 

 Strasbiirger, and of Woronin are not in the library ; consequently when at 

 last I saw them I found that most of my results had already been described. 

 But I found a few things which I take to be new. The branched hairs, 

 which in the young stage are in whorls round the stem, and in older stages 

 form a tuft in the centre of the pileus, are usually described and drawn as 

 consisting of distinct cells. I find, on the contrary, that the cavities of 

 the branches always during life remain in communication with one another 



