THE HAEMOFLAGELLATES 239 



the life-cycle of some or of all the parasites concerned has been 

 reinvestigated. (See Note below.) 



While preserving an open mind upon the matter, the writer 

 would point out that, if no indubitable confirmation of Schaudinn's 

 far-reaching conclusions can be said to have been furnished, the 

 merely negative evidence adduced by Novy and his colleagues is 

 by no means sufficient proof of their erroneousness. Because the 

 injection of cultures of certain Trypanosomes in artificial media, into 

 birds, was not followed by the appearance of Cytozoa in the blood, 

 these workers apparently conclude (Lc.) that there is no connection 

 whatever between these two groups of Haematozoa. And this com- 

 prehensive generalisation is put forward, although in nearly all cases 

 they failed to obtain even a Trypanosome-infection by this means, 

 apart altogether from the question whether the particular form with 

 which they did once succeed had itself an intracellular phase ! 



We will admit that the cultivation-method, which is of undoubted 

 use in other ways, may not be without value in studying the life- 

 history. In certain cases, for example, the behaviour of the parasites 

 on their arrival in the culture-medium may to some extent indicate 

 or suggest what happens when they pass into the Invertebrate 

 host, because of the general similarity of the physical conditions, 

 etc., to which they are at first subjected. An illustration of this 

 is afforded by the development of the Flagellate phases of the 

 Leishman-Donovan bodies in cultures. Nevertheless, we certainly 

 think that the value (in this respect) of the cultural method of re- 

 search is limited, and that great caution is necessary in drawing infer- 

 ences as to a parasite's life-history from the results obtained by it. 

 We dissent entirely from the American authors when they maintain 

 that the culture-medium is, for all practical purposes, the equivalent 



Note. The present writer has always been reluctant to think 

 Schaudinn made such a series of mistakes. It has always seemed to him 

 that this author's celebrated work on the Coccidia of Lithobius has not 

 been taken into account sufficiently by those who have maintained that 

 he was hopelessly wrong in the case of the parasites of the Little Owl. 



It is with the greatest pleasure, therefore, that on the point of 

 publication of this article, the writer is able to add that after a most 

 arduous investigation on the Haematozoa of the common chaffinch 

 (Fringilla coelebs), he has at length obtained the first definite and 

 unmistakable evidence, of which he is aware, in favour of one of 

 Schaudinn's conclusions. Here, there is only room to ?ay that, as a 

 result of his observations, he has now little doubt that a Haltcridium 

 parasitic in the chaffinch becomes actually, in certain phases, a little 

 Trypanosome ; in other words, that the Halteridium and the Try- 

 panosome which occur in this bird are onto^enetically connected (vide 

 Q.J. Micr. Sci. liii. p. 339, Feb. 1909). Hence the writer feels reassured 

 with regard to the truth of the corresponding part of Schaudinn's work. 



