120 PROTOPLASM 



tention by the fact that I have investigated material fixed in 

 alcohol, which easily becomes more or less plasmolysed. Had 

 he spent more time in attentively reading my work (which only 

 laid claim to the importance of a preliminary communication), it 

 would not have escaped him that I by no means used alcohol 

 only for preservation, but employed at the same time various 

 most excellent fixing media, such as picro- sulphuric acid, both 

 with and without osmic acid, chrom-osmium-acetic acid, osmic 

 acid vapour, etc., and that all these different media lead to 

 the same results essentially. If I usually employed weak 

 alcohol, with moreover, for the most part, an addition of iodine, 

 as a means of fixation, this was done because I had convinced 

 myself that it gave the same results as the remaining media, and 

 at the same time offered the advantage that staining methods 

 came off better and more characteristically in materials so fixed. 

 I can also certify that with proper application of this means of 

 fixation no plasmolysis is set up, but on the contrary there is 

 frequently, as I remarked, rather a tendency for the membrane 

 to burst with partial effusion of the contents. 



I consider it, however, quite unnecessary to spend any 

 more time over these things, since Fischer's quite unwar- 

 ranted objections can be contradicted without difficulty by a 

 series of facts which were just as accessible to him as to 

 me, and which he himself ought therefore to have taken 

 into consideration, had he thought it necessary to be 

 better informed upon these questions, before he delivered 

 judgment upon them. As is well known, the central body 

 or nucleus of the Oscillarice had already been observed by 

 E. Zacharias before me, and at a later date this investi- 

 gator followed up this matter further independently, but at 

 the same time as myself. Whether Fischer knows of 

 Zacharias's work or not remains uncertain, since lie nowhere 

 mentions it. In any case, Zacharias is as convinced as I 

 am, that the Oscillarian cell contains a central colourless 

 body of considerable size, and with peculiar properties. 

 Whether this body is to be interpreted as a nucleus or not, 

 is another question ; in any case, it is satisfactory that both 

 Zacharias and myself have obtained desirable results which 

 agree sufficiently on this point. I can be quite content if 

 Zacharias recognised this body as the forecast of a nucleus ; 

 for in that case it is also the representative of the nucleus 



