HERPETOMONAS ELMASSIANI. 335 



The object of using Lygcens was this: the limit of the range of 

 Oncopeltus fasciatus coincides with the limit of the range of the 

 plant flagellate, Herpetomonas elmassiani (Migone). But Lyg&us 

 is a very closely related insect, replacing Oncopeltus in the north 

 where the flagellates are not found. It was desired to know 

 whether it also had flagellates in its salivary glands. The 

 thirteen specimens of Oncopeltus, which came from Maryland in 

 September, 1924, at a time when the spread of plant flagellates 

 was going on rapidly, were all infected with the exception of 

 three individuals, which were rather young nymphs. The sixteen 

 specimens of Lyg&us were all negative for flagellates, both in 

 the intestinal tract and in the salivary gland. 



In the LygcBiis examined there were infections with sporozoa 

 in the glands, curiously enough in the same lobes frequented by 

 the flagellates of Oncopeltus. One of the species present in 

 Lygceus was occasionally seen also in Oncopeltus along with the 

 flagellates. But in Lygtzus the infections were much heavier, 

 and decidedly destructive to the gland cells which were penetrated 

 by intracellular stages and often rendered useless for secretion by 

 the growth of the parasites and the consequent death of the cells. 



The absence of flagellates in sixteen specimens of Lygtzus 

 collected at the end of the season was strikingly in contrast with 

 the presence of large numbers of flagellates in the glands of ten 

 of the thirteen Oncopeltus sectioned. If Oncopeltus is responsible 

 for the spread of the milkweed flagellate it is no wonder that the 

 spread is very rapid in September and early October when so 

 large a percentage of the then rapidly multiplying insects * are 

 positive. 



Of the original problems for the solution of which the histo- 

 logical work on Oncopeltus was carried out, but one remains for 

 consideration. Does the flagellate of Oncopeltus have more than 

 one stage of its life history in the insect? It seemed likely at 

 first that there would be developmental stages of the herpeto- 

 monad in the intestine. But no colonization of the intestinal 

 tract was indicated by any of my material. All the organisms 

 were in the glands. The question then arose as to the exact 

 position of the parabasal body in the forms colonizing the walls 

 of the salivary gland. Careful study showed that in all cases 



