PRESIDENTIAL ADDEESS — SECTION D. 189 



A theory regarding the nature of the cell which merits some 

 attention from all biologists is that of Altmann. This theory 

 was published by him in a number of detached papers, which, 

 though they have been noticed in various periodicals, have not 

 received a large share of attention. Now he has published the 

 results of his observations, and the theory he has deduced from 

 them, in an independent work, illustrated by a series of fine 

 plates.* Whatever be the value of the deductions of the author 

 regarding the essential character of the cell, he has at least 

 accumulated a number of valuable observations on cell-struc- 

 ture, which form a definite addition to our knowledge. 



The fully-formed cell, Altmann points out, is quite a com- 

 plex structure, and is by no means to be regarded as the 

 simplest organic element. The protoplasm of which a cell 

 consists is composed entirely of a series of minute particles 

 or granules, embedded in an intermediate jellylike substance. 

 These granules vary in shape, size, and optical characters in 

 different kinds of cells. In some cases they may be seen in the 

 li\ang state of the cells, but in most they are only brought dis- 

 tinctly into view by certain special methods of treatment. By 

 employing these methods, Altmann has been enabled to make 

 out the arrangement of the granules in a variety of different 

 kinds of cells. In some they lie isolated, embedded in a gela- 

 tinous matrix ; in others they are arranged in branching rows 

 to constitute series of fibrils, having various characteristics in 

 different types of cells. Fibrils are not present in every cell ; 

 granules are always present. 



The cell-nucleus is to be regarded as the matrix of the whole 

 cell. The connection between the contents of the nucleus and 

 the cell-body is shown not only by the radial structure of the 

 protoplasm, but specially by the phenomena of karyokinesis. 

 By the use of certain methods of staining, the nucleus shows 

 itself to be a mass of granules. The nucleolus usually lies in 

 little conglomerations of the intergranular substance, and the 

 net-formation of the intergranular substance goes out from this. 



This netlike intergranular substance also is not homogene- 

 ous, but when acted on in certain ways sometimes appears to 

 show symptoms of being made up of yet smaller elements 

 arranged in threads. In the course of indirect division the 

 separation between the substance of the nucleus and that of 

 the body of the cell is totally lost. 



While recognising the individual character of the cell, and 

 the all-important rule which it plays in organic structures, our 

 author points out that there are many organized bodies that 

 are not really cells, and attempts to trace the genesis of the 



* "Die Elementiirorganismen und ilire Beziohungcn zu den Zellen." 

 Leipzig, 1890. 



