UNIVERSITY OF CALIFORNIA PUBLICATIONS 



IN 



ZOOLOGY 



Vol. 18, No. 18, pp 509-519, 7 figures in text January 4, 1919 



NOTES ON THE EGGS AND MIRACIDIA OP 

 THE HUMAN SCHISTOSOMES 



BY 

 WILLIAM W. COST 



INTRODUCTION 



During the spring of 1917 through the kindness of Dr. J. P. 

 Hickey of the United States Public Health Service, I obtained fecal 

 samples from three cases of schistosomasis. One of these samples 

 contained eggs of ScJiistosoma mansoni and the other two contained 

 eggs of 8. japonicum. This material was used primarily for experi- 

 mental work, but gave an excellent opportunity for careful study of 

 the eggs and miracidia in the living condition. An examination of the 

 literature shows that, although the structure of the miracidium of 

 S. haematohium had been carefully worked out twenty-five years ago 

 (Looss, 1893, 1894), the descriptions and figures of this stage in S. 

 mansoni and S. japotiicum are still inadequate. 



THE EGG AND MIRACIDIUM OP SCHISTOSOMA MANSONI 



Figure 1 is a microphotograph of an egg of Schistosoma mansoni 

 showing its general shape and the position of the spine, and figures 2, 

 3, and 4 are drawings of the miracidium of this species, showing the 

 details of structure as they appear in optical section of the living 

 animal. It is interesting to note that in the egg the position of the 

 miracidium may be either with the anterior papilla toward the spine 

 (fig. 3) or away from the spine (fig. 4). Conor (1910, p. 533) noted 

 this same difference of position of the miracidium of S. haematohium 

 within the egg. In forty counts of this species he finds the anterior 

 papilla toward the spine and in one hundred and seventy, away from 



