28 



Fragmentation in Lineus gesserensis. 



ing of certain leaves is a material help to the translocation of starch 

 in them is probably sound, as such colouring matters screen off the- 

 rays which destroy the diastase. 



3. That there exists in plants a power of absorbing and utilising 

 the radiant energy of light, sometimes to a considerable extent, with- 

 out the presence of a chlorophyll apparatus. 



The last conclusion appears to be of very far-reaching importance, 

 supplementing other observations already published by Engelmann,* 

 Winogradski,f Speschnew, and other observers, none of whom, how- 

 ever, have indicated such utilisation of the rays of the visible 

 spectrum. 



" Fragmentation in Lineus gesserensis." By Alex. BliOWN,. 

 M.B., B.Sc, M.A., Lecturer in Zoology, and Senior Assis- 

 tant in the Natural History Department, University of" 

 Aberdeen. Communicated by Professor McIntosh, F.R.S. 

 Received February 1,— Read February 25, 1897. 



(Abstract.) 



The following results are deducible from the investigations 

 described in the paper : — ■ 



1. The zones of fission in Lineus gesserensis coincide with the- 

 transverse markings observable externally at definite intervals on its 

 body. 



2. The process of fission in all cases proceeds from within outwards,, 

 i.e.., from the digestive canal towards the cutaneous tissues. 



3. The process of fission is a process cf solution, and that, too, 

 through the agency of the digestive fluids of the alimentary tract. 



4. The solution of the tissues of the body-wall at the zones of 

 fission is preceded in those regions by circular outgrowths of intes- 

 tinal epithelium together with the formation of corresponding 

 external grooves. 



5. In the plane passing through any zone of fission, there is dis- 

 tinct evidence of the exertion of continuous pressure in opposite 

 directions, or pressure exerted outwards through the intestinal out- 

 growth is met by pressure exerted inwards in the same plane through 

 the body-wall. 



6. As the result of these opposing forces, atrophy, disintegration 

 and disappearance of the outermost cells of the intestinal outgrowth 

 take place. Thus the layers of the body-wall are brought into con- 



* ' Bot. Zeit.,' 1888. 



t ' Ann. de l'Institut Pasteur,' 1890—1891. 



