236 



Mr. R. J. Ludford and Dr. J. B. Gatenby. 



that we have based our results oa a broad foundation so far as concerns the 

 number of forms used, and the techniques by which the cells were prepared. 



The sections were prepared by J. B. G. and studied by both of us, but 

 E. J. L. is responsible for nearly all the drawings, and for a great share of the 

 task of finding mitoting cells. The drawings were made with the camera 

 lucida, and after careful discussion and an examination of numeroiis examples, 

 and great care has been taken not to vitiate our results by careless observa- 

 tion. This has been all the more necessary because the research has oEfered 

 considerable difficulties. 



We have to thank Dr. Da Fano for handing over to us his material of Mu& 

 testis from which the case of the rat spermatocyte divisions have been, 

 described. 



JSfote on the General Appearance of Besting and Mitoting Cells. 



Everyone who has worked with silver nitrate and osmic acid techniques 

 for the demonstration of the Golgi apparatus is well aware that these 

 methods may occasionally prove capricious ; but that such techniques really 

 do demonstrate bodies which are not artefacts and which can be seen intra 

 vitam, can easily be shown by comparing the images got by such methods, 

 with those live cells of the gonad of Helix or other molluscs. This should 

 still for ever the murmurings of the slipshod critics who have urged that 

 silver nitrate techniques should at all times be avoided. 



It is nevertheless true that quite often the formol-silver nitrate, and the 

 Kopsch techniques fail to demonstrate the apparatus, and this applies 

 especially to the Golgi apparatus of mitoting cells. This is the first point 

 which we wish to emphasize : it is possible to find resting and mitoting cells 

 side by side, with the Golgi apparatus beautifully clear in the former, and 

 apparently altogether absent in the dividing cells ; that the Golgi apparatus 

 is not really absent from the latter can be shown by the examination of 

 better impregnated material in which an apparatus will be found in mitoting 

 cells. But it seems quite certain that during mitosis, in some cases even in 

 the early prophases, the Golgi elements are altered in some way which makes 

 their demonstration quite difficult. 



The Golgi Apparatus in the Jnterkinesis Stage. 



As we have already noted, our material consisted of Stenohothrus viridulus 

 (a cricket) testis, of Helix and Limnaea ovo-testis prepared by Kopsch 

 and Cajal methods, of Eat and Cavia testis prepared by an osmic and a 

 formalin silver method. We possess also preparations of animals of every 

 other class in the Animal Kingdom (excepting Protozoa) which show the 



