32 



Scientific Proceedings (51). 



Bataillon, Mercier and many others to the leucocytes in producing 

 the phenomenon. Looss believes on histological ground, that 

 if leucocytes play any part in the process of tissue atrophy and 

 absorption, they play a minor and secondary one rather than a 

 primary r61e. The process of atrophy begins prior to the invasion 

 of the leucocytes into the muscle of the tail and this has been 

 described by Mercier and others, who hold that phagocytosis is 

 the principal factor. Moreover, it has been described for other 

 involuting organs, such as in the metamorphosis of insects, the 

 absorption of the gills of amphibia, etc. It has been suggested 

 for the involution of the mammalian uterus, likewise, so that it 

 may be said that investigators are in accord in observing a dis- 

 solution of the muscles and other tissues in atrophying organs prior 

 to the advent of leucocytes. 



It is to be expected that if phagocytosis plays any important 

 role in the inception of the process of absorption of tissue in the 

 larva of the frog, the blood would show an increase in the total 

 number of leucocytes during the stages of metamorphosis and 

 moreover there would be an increase in polymorphonuclear 

 leucocytes during these stages, to compensate for the drainage 

 of these cells into the muscles. In order to examine this point, 

 smears were made of the blood from the larvae of the bull-frog, 

 Rana catesbiana and from the western pickerel frog, Rana areolata. 

 Thirty specimens were used, the blood being permitted to flow into 

 a capillary tube from a lesion in the heart and then blown upon a 

 slide, dried in the air and stained with Wright's stain. A large 

 number of hematocytometer counts were made upon fresh blood, 

 but this method of estimation was abandoned on account of the 

 unsurmountable difficulty of recognizing the different kinds of 

 young corpuscles. As Freidsohn has shown, the various sorts of 

 leucocytes together with the erythrocytes take their origin from 

 cells more or less similar in appearance in the earlier stages, this 

 common stage resembling the large mononuclear leucocyte of the 

 human blood. 



The following table gives the summary of the differential counts 

 made upon the smears: 



Polymorphonuclear leucocytes are in slight advance in absorb- 

 ing individuals over those not yet metamorphosing, but there is a 



