448 THE AMEBIC AN NATURALIST [Vol. XL VI 



ever, do they approach the campanulate type. Putting 

 aside such stages, which, with a little practise, fall 

 naturally into place, the amount of further variation did 

 not prove to be great. The humps, both lateral and 

 ventral, on the smaller type, did show a considerable 

 amount of variation in relative size. And in numerous 

 cases it was of interest to note that such variations were 

 plainly hereditary ; i. e., an extra large female with, say, 

 relatively small humps, would contain a large young in- 

 dividual that was obviously of the same type. 



But these minor variations were to be expected; as 

 well as their tendency toward transmission, but they had 

 no evident connection with the type of change of which I 

 was in search. 



Of true transitional types I discovered but two possible 

 instances. These two individuals were quite alike, but 

 differed notably from any others of the thousands 

 studied. Each was, all in all, indisputably a humped 

 rotifer, but decidedly beyond the ordinary maximum size 

 and with disproportionately small humps. The corona 

 of each was much broader and its cells much heavier than 

 m any other humped individuals observed; the body 

 walls and musculature also were much heavier, taking the 

 deep stain shown otherwise only by the campanulate. 

 AD of these characters approached more or less the 

 campanulate type. Most striking, however, were the so- 

 called ovaries. In each case they were of the heavy type 

 shown by the larger rotifer. The nephridia did not 

 admit of careful observation. The most crucial organ of 

 all, however, the trophi, agreed wholly with the humped 

 type in form, and, though large, did not exceed the 

 maximum size found in the ordinary type. Studying 

 these two individuals with care, I came at last to the con- 

 clusion that, although in a sense they might be called 

 transitional, they were after all only variants of the 

 humped type— variants pointing toward, but not actually 

 leading to, the production of the campanulate type. 

 All in all, then,, my search for signs of genetic rela- 



