160 ZOOLOGY 



on the other hand, the injury is violent and sudden, disintegration 

 sets in rapidly before another surface film can form. The quick- 

 ness with which the new film is formed varies according to the 

 surrounding fluid. It is remarkably quick in the star-fish egg in 

 hypertonic sea-water (Chambers, 21). Another factor is the 

 condition of the protoplasm inside dependent upon external 

 conditions or upon its own specificity. 



Enough has been said to show that the cell wall cannot be 

 expressed entirely in terms of an interfacial film, but that it 

 possesses definite organisation and must be considered as a cell 

 organ. 



The results of Strangeways and Canti (122, 123) and others by 

 dark-ground illumination show a slightly different picture. They 

 state that there is no definite cell wall visible, although the outline 

 is sufficiently distinct. This we think is not contradictory to 

 Chamber's conception, because the organisation suggested is a 

 chemical and physical one of really minute proportions, and there 

 is no reason to suppose that optical differentiation of a sufficient 

 magnitude is likely to occur. 



A similar view is supported by the work of Gray on cell division. 

 According to him the dividing cell wall is actually laid down in 

 situ, i.e., organises itself. Separation into two is a mechanical 

 process subsequently carried out. If reference is made to the 

 case of the spermatocyte division figures given by Bowen (4) 

 when he refers to the cutting in two of the mitochondria, I 

 think it is clear that a similar explanation will fit that case equally 

 well (Fig. 64, C). Similarly, in the case of the nuclear-wall, all the 

 evidence of microdissection workers shows that it has a definite 

 organisation. Nearly all the experiments enumerated above on the 

 cell wall have been paralleled in the case of the nuclear membrane 

 with similar results. 



Any advance in our knowledge in this direction is likely to come 

 from the physiologist and from the biochemist. On the whole, 

 the microscope has been used to its optical and manipulative 

 limits. 



Pathological Cytology. A really adequate treatment of this 

 subject would require many more pages and more expenditure of 



