] ()'J MARTINI. 



merely liarbor this parasite and are not rendered visibly sick by ini'eeiion 

 with it. 



The foUowijig questions remained to be answered: 



1. Why did I not succeed in obtaining in culture media the dcvelo])- 

 mental forms of Koch from the piroplasmata of the "original calf"? 



2. Why did I not succeed in infecting with trypanosomata calves 

 Nos. 2, 4, 6, and 7 by means of the direct inoculation of the fresh blood 

 of the "original calf" without the use of culture media? 



In relation to the first question, it may be stated that a gi'owth from 

 the forms in the blood of the "original calf" into well-developed piroplas- 

 mata probably took place; however, these well-developed forms of Koch 

 were probably very rare as compared with the number of rod-shaped and 

 similar ones present in the blood (owing to the iinimal being relatively 

 immune though carrying the parasites) and for this reason they escaped 

 observation. Apparently this was also true in the case of calves ISTos. 2 

 and 4. The piroplasmata do not multiply typically in the culture 

 media, but only undergo a simple change in morphology, the meaning 

 of which is at the present time not fully known to us. In spite of the 

 most careful study I have never seen the parasites having rod-like and 

 similar forms develop into those which Koch described ; the former always 

 appear to disintegrate. Furthermore, it might be mentioned here that 

 I have not observed among the forms of the Manila piroplasma the 

 amoeba-like cells and those containing vacuoles which Miyajima describes 

 as being stages in the development of his piroplasma. I have likewise not 

 noticed the increase in size or the differentiation, in the ring forms 

 mentioned by him, so that such forms are not stages in the development 

 of the piroplasma I have observed. I believe, however, that I have seen 

 somewhat similar forms in incubated mixtures of noimal fresh blood of 

 cattle and bouillon. When the piroplasmata were present in enormous 

 numbers, as for example, in calves Nos. 4 and 7, I have seen them develop 

 in the culture media into the ray forms of Koch and to the forms with 

 chromatin points. However, when they were present in smaller number, 

 the developmental forms simply escaped observation. If there had been 

 an abundance of time which I had not needed for more important work, 

 I am convinced that I could have found these forms also in such instances. 



The second question with regard to the failure to infect with trypa- 

 nosomata the calves Nos. 2, 4, 6, and 7 by means of the inoculation of 

 fresh blood of the "original calf" can also be answered. The fact that, 

 in spite of the inoculation of cultures containing enormous numbers of 

 trypanosomata (as in the experiments with calves Nos. 1, 3, 5, 8, and 9), 

 I could not find trypanosomata in their fresh blood, even after centri- 

 fugation, sliows that the trypanosomata have undergone only a limited 

 multiplication in these animals which, therefore, must have a high degree 

 of natural immunity against the trypanosomata. This is shown even 



