302 U. B. FANTHAM. 



It should also be noted that Ziemauu (12), iu 1898, 

 very briefly mentioned the occurrence of chromatin in P. 

 bigeminum without figuring it. 



Schaudinu (1904), in a brief note at the end of his remark- 

 able memoir on Trypanosoma noctua) and Spirochaeta 

 ziemanni (9, p. 438), points out the presence of nuclear 

 dimorphism in P. canis and P. bigeminum. Liihe (4, 5), 

 in 1906, confirmed the observation as regards P. canis, and 

 further considered the question. Schaudinn and Liihe 

 described a large mass of chromatin, the " principal" nucleus, 

 and a smaller, dense, punctiform mass of chromatin, which 

 Schaudinn suggested was homologous with the blepharopiast 

 of a Trypanosome, to which Liihe agrees. 



Lastly, Nuttall and Graham-Smith (8), in October, 1906, 

 also saw these two chromatin masses in P. canis, and, in 

 addition, a third mass of loose chromatin, described by 

 them for the first time. 



My own observations on the chromatin of P. bigeminum, 

 as seen more especially in blood from the heart-muscle, may 

 now be set forth. 



IV. The Chromatin Masses of P. bigeminum. 



The observations to be described wei'e always made on 

 those parts of the preparation which appeared well fixed 

 aud properly stained, especially in so far as the parasite was 

 concerned. 



It may be stated at the outset that to give a general 

 account of the distribution of the chromatin, which might 

 be taken as the average or type, is difficult, as considerable 

 variation Avas noticed. This variation has been already notified 

 by Nuttall and Graham-Smith (8) in the case of the chromatin 

 of P. canis, a species larger than P. bigeminum. It would 

 seem best, then, to illustrate, by accurate diagrams, as many 

 different forms as possible, at the same time noting their 

 relative frequency of occurrence. 



