800 REPORT — 1894. 



uniform nature, since there is this one point within the cell that exerts a special 

 attraction upon the rest of the cell-substance ; and, indeed, on this account the 

 particle has come to be termed the ' attraction particle.' And in the second place, 

 because of the apparent universality of the occurrence of such a particle. And, 

 thirdly, because of the fact that one of the most important phenomena exhibited 

 by the cell hinges upon the behaviour of this particle ; for it is found that before a 

 cell or its nucleus divides this minute attraction particle begins by itself dividing, 

 and is, in fact, more commonly met v?ith double than single. Nor is it until the two 

 particles thus produced have evolved, either from themselves or from the substance 

 of the protoplasm or nucleus, a system of communicating fibres, the so-called achro- 

 matic spindle, that those changes in the imcleus and protoplasm take place which 

 produce the division and multiplication of the cell. This attraction particle, which 

 is also called the central particle or centrosome, has absorbed so great an interest 

 that, short as is its history, many papers have already been devoted mainly to it, the 

 latest of these being an elaborate treatise of some 300 pages by Martin Heidenhain. 

 I shall not here attempt to follow out the details of all these researches, but will be 

 satisfied with putting before you the conclusion which Heidenhain has come to re- 

 garding this particle, viz., ' that it is morphologically, physiologically, 

 and chemically a structure sui generis; not merely a separate 

 portion of nucleus or of protoplasm, but an organ of the eel 1 

 with definite functions, and having a definite existence of its 

 own.' Nevertheless, it is almost as minute an object as it is possible to con- 

 ceive. In a cell which is magnified a thousand diameters the central particle 

 appears merely the size of a pin-point. Yet this almost infinitely small object 

 exerts an extraordinary influence over the whole cell, however large (and the 

 cell may be many thousand times its size), for it initiates and directs those 

 processes which result in the multiplication of the cell, and indirectly, therefore, it 

 is concerned in directing the general growth of the individual, and ultimately the 

 propagation of the species. 



A former President of the Association took as the subject of his presidential 

 address what he was pleased to call the ' Next to Nothings.' In considering this 

 central particle, of the actual structure of which, and of its chemical constitution, 

 we know at present hardly anything, we may surely regard it as a striking instance 

 of the supreme importance of the ' next to nothing ' in Physiology. 



The other subjects to which I desire to draw your especial attention relate to 

 the physiology of certain organs the functions of which have always been extremely 

 obscure, and which, although they differ greatly from one another in almost every 

 point of structure, and presumably also in function, it has been usual to group 

 together under the name of ductless glands. The name ' gland ' is given to such 

 organs of the body as take materials from the blood, and convey those materials 

 in an altered or unaltered form, by a tube or duct, to a surface either internal or 

 external. Such material is termed the secretion of the gland, and has for its object 

 either the performing some function which is useful to the organism or the getting 

 rid of material which would be detrimental if retained. In the case of the ductless 

 glands there is no such possibility of pouring out material produced by the gland 

 upon a surface, because these organs do not communicate with any surface by a 

 duct ; and whatever material they may furnish must therefore, if it is to re<ach the 

 body generally, pass into the blood ; that is to say, the blood on the one hand 

 must furnish the materials for the secretion of the gland, and on the other hand 

 it must take up those materials after they have been manufactured into something 

 else, and carry them away to other parts of the body. Now, in the case of a 

 certain number of the ductless glands there has not appeared to be any very great 

 obscurity as to their function ; for some of them seem very obviously to be devoted 

 to the formation of corpuscles which are found within the blood itself. But with 

 regard to others of these bodies it has not hitherto been possible to find any special 

 material in the blood which they have furnished to it, and our knowledge of 

 them is derived almost entirely from experiments. I will take the case of two 

 of these to illustrate the vast influence which small and almost disregarded 

 organs may exert upon the whole economy. But in the first place I may be per- 



