142 Jdiinial lit Entdiiiolcitjy and Zodlofiv 



The work already done leading towards a comprehension of 

 these problems, if not their solution, has been with many groups of 

 animals, including a few vertebrates. My papers dealing with one 

 or another phase of the nervous system of invertebrates ha\-e been 

 published in a number of places. Much unpublished work includes 

 other material, but only a beginning has been made with the inves- 

 tigations which will be necessary for an ad\anced step in this ciirec- 

 tion. Some of the work so far, is necessarily of a fragmentary 

 nature and much of the gross anatomy particularly, merely confirms 

 the labors of many in the past. Part of the reason for studying 

 so many forms is to extend my own knowledge so that I may have 

 first-hand experience with all types. Part of the reason for special 

 study here and there is to clear up doubtful points or is directed 

 towards some particular problems in which an animal or group of 

 animals seems to offer special advantages in the way of suggestion 

 or solution. Hardly a form considered in any way but that brings 

 out some important fact, some previously unpublished suggestion. 

 Each separate in\'estigation then may contribute a small part in 

 itself, but each study is directed toward the larger end of attempt- 

 ing to solve some of the most intricate and ciifHcult problems of 

 Biology. More than one line of in\estigation is being followed, 

 but necessarily the groundwork of future activity must be laid upon 

 anatomical and developmental studies. Other methods are used 

 or are to be used as necessity dictates and such as naturally develop 

 in connection with the attack upon the central problems. 



Some of the specific questions which ha\e been in mini] from the 

 start are as follows: 



1. What is the relation which exists between cell and cell in 

 the centi-al ner\'ous system? Do cells merely run in contact, 

 or is there an organic connection between them, or are both 

 things true? 



2. What part does the nucleus play (a) in conduction and (b) 

 in general metabolism of the cells? 



.1. How are the fibi-ils related (a) within cells ami (b) outside 

 of cells? 



4. What is the fibrilar structure of (a) the cell-body and (b) 

 of the material between cells? 



