694 OEDEK: DIPLOMONADIDA 



writer's opinion, appears to be the arrangement : All the blepharoplasts and 

 axonemes have a superficial position on the ventral surface of the body. 

 Between the two oval nuclei, which are also near the ventral surface, 

 and slightly anterior to them, are four blepharoplasts arranged in pairs on 

 each side of the middle line of the body. The lateral blepharoplast of 

 each pair is slightly posterior to the one which is more centrally situated. 

 Unless the stain is sufiiciently extracted, each pair appears as a slightly 

 elongated single blepharoplast. From the lateral ones there arise two 

 axonemes, which pass forwards and, taking a curved course, cross one 

 another. They reach the border of the sucking disc, pass along it for some 

 distance, and finally enter flagella at points on its outer margin. From 

 the median blepharoplasts there also arise two axonemes, the so-called 

 axostyles, which pass backwards either on the surface of the body or just 

 beneath it to the posterior extremity, to be continued into the posterior 

 flagella. From these anterior central blepharoplasts there also arise two 

 fibres which pass forwards and towards one another. They unite after a 

 short course, and are continued as a single fibre, which is lost in the 

 cytoplasm of the anterior part of the body. The single fibre sometimes 

 appears as a group of radiating fibres. There is another pair of blepharo- 

 plasts centrally placed on the surface of the body in the hollow of 

 the notch in the sucking disc. From them arise two axonemes which 

 immediately enter flagella, which appear to arise directly from the 

 blepharoplasts. 



It seems probable that there is still another pair of blepharoplasts, 

 from which the axonemes of the fourth pair of flagella originate. The 

 axonemes of these can be traced forwards along the margins of the notch 

 in the sucking disc, and can often be seen to terminate in a pair of 

 granules at the anterior end of the notch. These are not improbably the 

 blepharoplasts, which, however, appear to be connected with the anterior 

 lateral blepharoplasts by fine fibres. If the granules are not the blepharo- 

 plasts, then it must be assumed that the fibres which connect them with 

 the anterior lateral blepharoplasts are continuations of the axonemes, and 

 that they terminate in the blepharoplasts from which originate the 

 axonemes of the anterior crossed flagella. Not infrequently, granules may 

 be seen in stained specimens at the point of entry of the axonemes into 

 the flagella. This is particularly true of the posterior flagella, but these 

 granules probably indicate a thickening of the superficial layer of cyto- 

 plasm or periplast, and cannot be regarded as blepharoplasts. In the 

 arrangement, as just described, there can be distinguished a pair of lateral 

 crossed flagella, the axonemes of which arise from the anterior lateral 

 blepharoplasts; a pair of lateral uncrossed flagella with axonemes arising 

 from the same blepharoplasts, or more probably from others posterior to 



