THE DEVELOPMENT OF FASCIOLAKIA. 15! 



With the aid of such evidence as I have been able to obtain, 

 and Osborn's interesting discovery ('04) of amitosis in the endo- 

 derm, I think I may formulate a scheme to account for the 

 transfer of materials which probably takes place. Osborn ('04) 

 announced that he had discovered amitosis in the endoderm of 

 the gastrula^ of Fasciolnria and associated, very justly, I think, 

 these nuclear phenomena with digestion. I have been able to 

 verify these results, not, however, until I had been thoroughly 

 led astray by the assertion that the nuclear divisions in question 

 occur in the gastrula stage. All my earlier larvae show no signs 

 either of the " cuboidal endoderm" or of the amitoses of which 

 Osborn speaks. The latter phenomenon I finally discovered in a 

 larva that had a velum, and was therefore well past the period of 

 cannibalism. Fig. 8 is compounded from several sections ob- 



vei 



op cp. 



FIG. 8. Composite figure made up from several adjacent sections oblique to the 

 antero-posterior axis. The external kidneys, not yet subvelar in position, are cut 

 horizontally. Opsp., optic cup. vel. , velum. The arrows are intended to indicate 



the probable paths of waste products reaching the exterior from the digestive tract 



? obj. 3 oc. 

 seen in transverse section, via the external kidneys. Leitz 



lique to the antero-posterior axis of this larva. The oesophagus 

 is cut transversely and the cells which compose it are dorsally, 

 large, polynucleated, and highly granular, with vacuoles at their 

 distal ends. The nuclei appear to have arisen amitotically. 

 Some of these cells have burst and their contents may be seen 

 oozing out. They bear a striking resemblance to the cells of the 

 external kidneys. 



The cells of the lateral and ventral walls of the cesophagus 

 have a very different appearance. These, instead of being long 



