ON DREPANIDIUM RANARUM. 65 



spleen-pulp with a fixing acid (such as osmic or nitric), may so 

 ati'ect the blood-corpuscles and spleen-cells and the Drepanidia 

 themselves as to cause the latter to stain more readily in the 

 former than in the latter case. 



The mere fact (supposing it to be a fact) that the Drepanidia 

 are more readily demonstrated in a preparation which has been 

 treated when fresh with salt-solution than in one which has been 

 treated when fresh with osmic or nitric acid, cannot be admitted 

 as affording any sufficient basis for assuming the existence in 

 nature of a transmutation of organic forms such as that advo- 

 cated under the name " Heterogeny " by Pouchet and Bastian, 

 and for rejecting the obvious agreements both in form and 

 habits of our Drepanidium with the falciform young stages of 

 the Sporozoa or Gregarinida. 



Post-scriptum. — I think it useful to point out on the present 

 occasion that the views put forward with reference to another 

 parasite of the Frog's blood, viz. the Trypanosoma sanguinis, 

 by the same author, Dr. Gaule, whose speculations as to 

 Drepanidhim have just been discussed, are as novel as the 

 latter. Having given some care to the study of Trypanosoma 

 (which I described under the name Undulina, believing it to be 

 an unrecorded organism), I am of opinion that Dr. Gaule's 

 views as to that parasite are devoid of justification. 



In the 'Archiv der Physiologic,' 1880, p. 375, Dr. Gaule 

 propounds the view, which he illustrates by a plate, that this 

 curious httle parasite is a modified colourless blood corpuscle. 

 Dr. Gaule appears to derive some special satisfaction from 

 launching startling suggestions of this kind based upon the 

 smallest amount of evidence. His ground for concluding that 

 Trypanosoma is a modified blood-corpuscle is simply that he 

 observed in Frog's blood abnormal colourless blood-corpuscles 

 vaguely simulating the form sometimes presented by Trypano- 

 soma. At every step of his statement of inferences and 

 arguments on this subject Dr. Gaule appears to me to be 

 inconsequent. 



VOL. XXII. NEW SER. 



