494 



Mr. C. E. Walker 



[Aug. 2, 



I have to thank Professor Sherrington for his kind advice, which has been 

 of the greatest value to me, particularly when beginning my researches with 

 regard to leucocytes. 



[Addendum, July, 1907. — I would take this opportunity of pointing out 

 the relationship between certain structures which arise from true archoplasms. 

 Among such structures are the archoplasmic vesicles found in the cells of the 

 testis, which develop into the cephalic cap of the spermatozoon ; the similar 

 structures (Plimmer's Bodies) which appear in some of the cells in malignant 

 growths ; and the granules in leucocytes. Whether these phenomena are 

 connected in some way with the Maiotic Phase is not clear, though something 

 of the kind would seem to be suggested. 



Since the above communication was presented, my attention has been 

 redirected to a communication by Professor Mathews, of Chicago University, on 

 " The Changes in Structure of the Pancreas Cell."* I give the following 

 summary of the results obtained by Professor Mathews and myself. 



Mathews. 



(1) Certain spiral twists or coils 



are found in the cytoplasm of the 



pancreas cells at certain periods. 



They probably arise from the nucleus. 



(2) The threads, or some of them, 

 subsequently collect in a mass, form- 

 ing the " so-called nebenkerns of the 

 pancreas." 



(3) These spiral twists or threads 

 ■proceed to decompose. 



(4) A stage apparently intervenes 

 between the disappearance of the 

 threads and the appearance of the 

 granules in any given portion of the 

 cytoplasm of the cell. 



(5) It is probable that the " zymo- 

 gen granules and the cytomitoplasm 

 of the inner zone arise as the products 

 of the decomposition of the threads." 



* ' Journal of Morphology,' vol. 



Walker. 



An archoplasm, i.e., an area in the 

 cytoplasm snowing a denser and more 

 homogeneous structure than the rest, 

 is found in certain leucocytes. This 

 archoplasm does not arise from the 

 nucleus. 



A coiled up thread, arising in the 

 archoplasm, may be observed in some 

 leucocytes. The archoplasm in the 

 leucocyte is something entirely 

 different to the " nebenkern of the 

 pancreas cell." 



The coiled archoplasmic thread 

 proceeds to grow until it surrounds 

 and obscures the nucleus. So far 

 from any decomposition taking place, 

 there is never any cessation in the 

 growth of the thread until it has 

 invaded the greater part of the 

 cytoplasm. 



The thread breaks up directly into 

 a number of short lengths, which 

 subsequently acquire an oval, and, 

 later, perhaps a spherical shape. 



The granules found in the leuco- 

 cytes described arise by the direct 

 breaking up into definite segments of 

 the thread. In these cells there is no 

 cytomitoplasm, and the thread from 

 its first appearance never shows any 

 sign of decomposition. 

 15, 1899, Supplement. 



