738 William Patten 



Siilplmric acid Ims proved to be a most valuable macerating-, as 

 well as preservative reageut. In weak solutioiis (40 drops to 50 grams) 

 eiitire Molluscs. witliout the sliell, bave beeu kept iu a perfect state of 

 preservatioii for more tbaii six niontbs. For cilia and nerve endings, 

 it is exceptionally good. Besides preserviug the lens, which may sub- 

 seqiiently be isolated in perfect condition . it has beeu of great vaine 

 iu isolating tbe entire retina, the different layers of wbicb may tbeu 

 be studied «in toto«. 



In the study of the eyes of Arca as well as those of Pecfunculus^ 

 I bave had special recourse to raaceratiou of the eyes either in 

 Müller's fluid or chromic acid. I find that the use of undiluted 

 Müllers fluid for 24 bours gives more satisfactory preparations tlian 

 a weak solution for a longer period. Chromic acid (V5V0) for 10 or 

 12 days gave most of tbe preparations from which my drawings of tbe 

 nerve endings werc made. I bave found that a few drops of acetic and 

 osmic acid added to di stili ed water give a very energetic macerat- 

 ing fluid for the epitbelium of marine Mollusca. It was in prepara- 

 tions made in tbis way that I first observed, in the comiìonnd eyes 

 of Arra^ the very delicate contiuuations of the inner ends of the pig- 

 mented cover cells to tbe outer surface. My studies upon this sub- 

 ject bave convinced me of the very great importance of a thorougb 

 control over a good method of isolating the cells. I bave not found 

 auy method by which ali the structures of the cells could be equally 

 well preserved; it was, therefore, necessary to use several different 

 macerating fluids in order to discover the effects of each fluid upon the 

 individuai elements , so that by comparison we might distinguish 

 between tbe pathological and normal cbaracters. Besides preparations 

 of isolated cells, I bave studied sectious of the mantle edge fixed in 

 picro-cbromic-osmic (Fol), and chromo-acetie-osmic acid, as well as 

 in picro-sulphuric acid. 



Die Redaction erlaubt sich zu pag. 1)87 eiuc Anmerkung. Während des 

 Druckes der PATTEN'schen Arbeit hatten die Herren Paul Mayek und Wilh. 

 GiESBRRCHT die hier seltene Gelegenheit, 3 große lebende Exemplare von Enphan- 

 sia (1 Q mit Embryonen) zu untersuchen. Isolirte und während der Beobachtung 

 mit dem zusammengesetzten Mikroskope unter dem Deckglase zerquetschte Brust- 

 augen leuchteten stark; das Licht strahlte höchstwahrscheinlich vom Stäbchen- 

 biindel aus. Ein unverletztes Thier wurde in der Rückenlage mit Ammoniaklösung 

 gereizt; sofort traten sämmtliche sog. Augen als eben so viele leuchtende Punkte 

 hervor, während der Rest des Körpers dunkel blieb. Etwa 1,2 Minute lang leuchteten 

 die Brust- und Biiuchorgane äußerst lebhaft, die Organe iu den Stielen der zu- 

 sammengesetzten Augen schwächer; selbst im Halbdunkel waren die blaugrünen 

 Lichtpunkte mit bloßem Auge deutlich sichtbar. Die Angaben von Sars erfahren 

 hierdurch eine Bestätigung. 



