518 Chapter XVI 



clearly it was necessary to bring forward exact experimental proof. 

 I set myself, therefore, during my stay at Messina in 1882 and 

 1883, to study the role of the amoeboid cells of the mesoderm 

 from the point of view of intracellular digestion. I found it an 

 easy matter to demonstrate that these elements seized foreign bodies 

 of very varied nature by means of their living processes, and that 

 certain of these bodies underwent a true digestion within the amoeboid 

 cells. My principal thesis, that is to say the idea of the intimate 

 relations between the entoderm and the mesoderm, was thus fully 

 confirmed. 



Pondering over these results, which were quite new at the time, 

 the idea suggested itself to me that the digestive function, so pro- 

 foundly rooted in the mesodermic elements, must play a part in many 

 of the vital phenomena of animals. Starting from this standpoint, I 

 succeeded in demonstrating that, during the very complicated meta- 

 morphoses of Echinoderms, such as the Synaptae, the amoeboid cells 

 of the mesoderm fulfil a function in the atrophy of numerous larval 

 organs. I have never prosecuted any medical studies; but some 

 time before my departure for Messina I listened to the reading of 

 Cohnheim's treatise on General Pathology, and I was struck by his 

 description of the facts and of his theory of inflammation. The 

 former, especially his description of the diapedesis of the white 

 corpuscles through the vessel wall, seemed to be of momentous 

 interest. His theory, on the other hand, appeared to be extremely 

 vague and nebulous. It occurred to me that a comparative study of 

 inflammation in lower animals of simple organisation would certainly 

 throw light on the very complex pathological phenomena in the 

 Vertebrata, even in the frog which had served as the starting-point 

 for Cohnheim's remarkable experiments. 



Since, in the atrophy of the larval organs of the Synaptae, the 

 essential role is accomplished by the amoeboid cells of the mesoderm 

 which accumulate and unite into masses, the richness of inflammatory 

 exudations in white corpuscles may perhaps signify that these cor- 

 [542] puscles have a very important function to fulfil. This reflection led me 

 to make the following experiment : to wound and introduce spines be- 

 neath the skin of very transparent marine animals ; if my hypothesis 

 should be well founded this should bring about an accumulation of 

 amoeboid cells at the injured spot. I selected for this purpose the 

 large Bipinnaria larvae of star-fish, so abundant at Messina, and 

 inserted prickles of the rose into their bodies. Very shortly these 



