1905.] On the Cytology of Malignant Growths. 347 



In animals, as has already been stated, it invariably happens that, after the 

 onset of the first maiotic (heterotype) mitosis, there ensues only one further 

 nuclear division, commonly designated as the homotype, on account of its 

 close general resemblance with a normal somatic mitosis. The principal 

 point of constant difference lies in the retention in the former of the reduced 

 number of chromosomes. The cells originating from this division give rise 

 after a more or less complex series of changes of form and of the inter-relation 

 of their constituent parts and the sexual cells without any further intervening 

 nuclear divisions. In plants this is not the case. The cells issuing from the 

 homotype mitosis always undergo one or (often) many subsequent divisions 

 before" some or all of the resulting units develop into sexual cells. It is 

 therefore of interest to find in cancerous tissue that there is abundant 

 evidence that the cells, the nuclei of which have undergone reduction, are 

 capable of continued division, and, indeed, a great part of the tissue of the 

 cancer is made up of such cells, which, in accordance with the terminology we 

 have elsewhere employed, we may term post-maiotic, or " gametoid." 



It will be seen that we differ from Von Hansemann in our explanation of 

 these " hypochromatic " nuclei, regarding them as have arisen, not as the 

 author just named believes, by a dropping-out of chromosomes from the 

 spindle, or through some form of degeneration, but chiefly as the result 

 of a process resembling, or identical with, that by which reduction is 

 ordinarily effected in the tissues destined to give rise to the gametic cells. 

 But we desire to definitely state that, in using the term "gametoid," we 

 expressly differentiate between the cancerous cells and those of normal 

 reproductive tissues. The relation existing between them, if any, is at 

 present obscure ; and, though we think the resemblances, which will be still 

 further emphasised by facts we are about to describe, are very suggestive, we 

 are far from holding the views which have been expressly or implicitly 

 ascribed to us by other writers as to the identity of gametic with " gametoid " 

 cells and tissues. 



Finally, then, it is clear that there exist in the facts of pluripolar mitosis, 

 on the one hand, and in amitosis on the other, a mechanism sufficient to 

 explain all the irregular numbers encountered in a young cancer. But the 

 irregularities, while masking, cannot conceal the far more frequently recurring 

 numbers of chromosomes, whereby the reduced (halved) and, though far less 

 frequently, the double, numbers become apparent. But the existence of the 

 irregularities indicated above often renders extremely difficult the task of 

 deciding to what category a particular departure from the normal somatic 

 number is to be relegated. 



There is a further body of evidence bearing on the resemblance between' 



