ON DREPANIUIUM RANARUM, 63 



1. That tliey exhibit active movements under circumstances 

 usually favorable to the movements of the Protozoa and 

 Protophyta. 



2. That they occur within the cells of the organism in 

 which they are found as well as in its fluids. 



3. That they are present in some Frogs and not in others, 

 living under approximately the same conditions. 



■i. That they vary in abundance in the same Prog, examined 

 at different times. 



5. That they are abundant at one time of the year, and not 

 at another. 



6. That they are seen on the stage of the microscope to 

 penetrate and enter cells by means of their active movement. 



7. That they are also seen to escape from cells by the same 

 activity. 



8. That they are localised chiefly in the spleen, though not 

 confined to that organ. 



9. That though most abundantly observed in certain speci- 

 mens of lla7ia esculenta at Leipzig, yet they have also been 

 observed in Rana temporaria and in Triton sp. 



These observations are not merely consistent with the view 

 that Brepanidium is an independent parasitic organism, but are 

 directly in favour of that view ; since they are readily explained 

 if that view be admitted, whilst they remain as isolated and 

 unconnected facts, each requiring a special assumption for its 

 connection with any other theory which may be advanced as to 

 their nature, when the obvious one that they are parasitic 

 organisms is rejected. 



The only fact which Dr. Gaule adduces which is inconsistent 

 with the parasitic nature of Drepanidium is that in some cells — 

 especially blood-corpuscles — these bodies are not present when an 

 examination of them is first made on the field of the microscope, 

 and that on the addition to the preparation of ''6 per cent, solution 

 of sodiitm chloride the " Wiirmschen" are formed there and then 

 in the cells. 



I take the liberty of doubting altogether the accuracy of Dr. 

 Gaule^s statements on this point. The supposed fact is not a 

 fact, but an erroneous interpretation of an observation. 



It is not so long ago since the view was maintained by accre- 

 dited physiologists that the nucleus of the Prog's red blood- 

 corpuscle did not exist during life, and only came into existence 

 as 2i post-mortem product of commencing disintegration. 



We now know very well that there are appearances which 

 favour such a notion with regard to the nucleus. The nucleus 

 is very frequently not visible in the Prog's red-corpuscle during 

 life, and becomes visible as the result of the first changes in 



