682 president's address. 



to the latter. The structure of protoplasm is vesicular or frothy ^ 

 and its movements are due to purely mechanical forces similar to 

 those that operate in bringing about the movements in our drop 

 of frothy emulsion. 



That the probability of this is established as regards some forms 

 of protoplasm and some protoplasmic movements can hardly be 

 doubted. But there is danger lest we imagine that this conclusion 

 cai'ries more with it than it really does. It is important to know 

 that some of the movements of protoplasm can be explained in this 

 way ; but in accepting this explanation we must guard against 

 the idea that we are thei'eby making an important step in the 

 direction of destroying the conception of vitality as distinguished 

 from a peculiarly subtle and complex combination of chemical and 

 physical forces. The only conclusion that the vitalist will admit 

 to be capable of being legitimately drawn from such experiments 

 is that some of the movements of living protoplasm may not be 

 vital. 



That protoplasm is in many cases of a vesicular, alveolar, or, as 

 Prof. Biitschli prefers to call it, foamy, nature will be granted 

 readily enough by all who have given attention to the subject. 

 But that all that we observe of structure in the cell — whether of 

 the lowest organisms or of the highest — is brought about merely 

 by this vesicular arrangement, is not to be so readily conceded. 

 When we come to take special cases and to attempt to interpret 

 them in accordance with this theory, we soon come to meet 

 with many difficulties. That some part of what we often take 

 for reticulate and fibrous structure may really be due to the 

 vesicular nature of the protoplasm is probable enough ; it may 

 also be conceded that some of the striations observable in the cell 

 may have resulted from x-egular streaming movements of the 

 protoplasm leaving rows of vesicles ; but a wide difference exists 

 between admitting this and subscribing to the view that all 

 cytoplasmic structure is capable of this explanation. 



For in examining specialised cells of a size to render their study 

 favourable for the interpretation of minute structure, we find 

 appearances which, as it seems to me, are not capable of being 



