192 PEOCEEDINGS OF THE SOCIETY, 



went on to say that cytologists would not be carried mucli farther- 

 without great improvement in the manufacture of microscope lenses, 

 and even if things were much improved it was doubtful if they would 

 see much more structure. It seemed strange to hear that the silver 

 nitrate reductions were extremely capricious and great care must be taken 

 in the interpretation of the images given. Another point was that the 

 present list of fixatives and methods of technique for the representation 

 of cell structure was already overcrowded, and, in his (the speaker's) 

 opinion, required to be weeded out. He was recently exhibiting at a 

 Conversazione at King's College some successful specimens of ForficuJa 

 auricularia (common earwig) which clearly showed centrosomes and 

 spindle fibres. Dr. Ross, who was present at that Meeting, was asked tO' 

 look at the preparations. Dr. Ross gave little time to the examina- 

 tion, but quickly pronounced the resnlts shown to be due to artefacts. 

 Being surprised at this statement further attempts were made ni order 

 to show these spindle fibres and centrosomes under as nearly living con- 

 ditions as possible. By the following August he had been able to gain 

 a certain amount of expertness in getting out the testes of the earwig ia 

 about three-quarters of a minute. While they were under survey it was 

 easy to see the spindle fibres and centrosomes. The standard of living- 

 condition was judged by the motility of the flagella of the spermatozoa. 

 While they were in active movement the cells were considered to be 

 living ; as soon as the motion ceased the cells were looked upon as dead 

 and disregarded for further observation. He considered that to be 

 sufficient evidence that the spindle fibres and centrosomes were cytological 

 facts, and not the result of artefacts. After establishing a fact like that, 

 there were no limits as to what might be seen under dark-grounfi 

 illumination. It should be quite possible to see structures such as Mr. 

 Gatenby had described. 



Dr. Murray said that the mitochondria could be seen by means of 

 dark-ground illumination, and the evidence was very convincing. He 

 was particularly interested in Mr. Gatenby's work, and believed it would 

 lead them to more knowledge on the subject. 



Dr. Da Fano also spoke. 



Mr. Gatenby, in replying to the discussion, said that they had been 

 able to see that evening that there was such a thing as the Golgr 

 apparatus, and the mitochondria could be seen by dark-ground illumina- 

 tion. The point was whether the mitocbondrium was a fact ; whether 

 the Golgi apparatus was a fact. It would be very nice to have them of 

 a beautiful shape — but there they were. They were grotesque shapes, 

 and he had had nothing to do with the making of them. The spindle 

 fibres did not come into the question. He had not done much in dark- 

 ground illumination ; he had tried the mitochondria with it, but found 

 that the cell had to be particularly big before one could get far with it. 

 But he had watched the mitochondria in the living cell with ordinary 

 illumination. It had been shown that the mitochondria move about, and 

 they had been watched intra vita in the living cell. Tracing the Golgi 

 apparatus through had been worked out by himself and another in a 

 mollusc. The Golgi apparatus had been traced to the primordial nerve- 

 ganglion in the mollusc. 



