336 Prof. Farmer, Messrs. Moore and Walker. [Nov. 17, 



this group, appears, under artificial conditions, unable when expelled from its 

 burrow to re-establish itself in a new home. It is, therefore, interesting to 

 enquire what influence evokes the reconstruction of the abdominal segments, 

 alike whether the fragment be confined within its tube or free as in 

 a watch-glass. 



On the Cytology of Malignant Growths. 



By J. Bretlakd Farmer, F.R.S., J. E. S. Moore, A.R.C.S.. and 

 C. E. Walker. 



(Received November 17, — Read December 7, 1905.) 



[Plates 8—12.] 



In the winter of 1903 we presented to the Royal Society a preliminary 

 account of the results of our investigations on the cytology of malignant or 

 cancerous growths, in which we stated that we had recognised a certain type 

 of nuclear division, known as the heterotype, to occur in the cells of these 

 pathological tissues. Hitherto, this peculiar kind of mitosis, characterised 

 by a reduction to one-half of the normal number of the somatic chromosomes, 

 together with highly characteristic forms of their bodies themselves, had only 

 been known to occur in connection with the so-called reduction division, 

 that, in animals, immediately precedes the formation of the sexual elements. 

 These reduction divisions constitute a well-known phase in the life cycle of 

 all higher animals and plants, consisting invariably of two consecutive 

 stages, which are distinguished as heterotype and homotype mitoses respec- 

 tively. As these two mitoses constitute so well-defined a stage in the 

 cellular life history 7 of the higher organisms, we have proposed to emphasise 

 this fact by the introduction of the term " maiosis," designating the stage 

 itself as the maiotic phase. Thus the heterotype and homotype mitosis form 

 respectively the first and second maiotic division. 



We propose, in the present paper, to deal more fully with the cytological 

 details of malignant growths, in so far as we have been able to investigate 

 them, and we shall endeavour briefly to point out the conclusions that we 

 think may legitimately be drawn from them. In doing this we desire, as far 

 as possible, to confine ourselves to a consideration of the evidence we have 

 been able personally to obtain, and we propose to avoid a general discussion 

 of the numerous theories as to the aetiology of the disease, and especially of 

 those that are based on clinical experience, except in so far as our own 



