THR H^MOFLAGELLATBS. 269 



it is intermediate, in short, between the acicular forms and the 

 genus Crithidia, characterised by its pyriform shape. The 

 kinetonucleus may apparently be either near the anterior end 

 or near the trophonucleus ; but L, does not mention the 

 occurrence, in the latter case, of any rudimentary membrane. 

 We come next to Crithidia fasciculata, which Leger 

 found in the intestine of Anopheles maculipennis 

 (females). A striking resemblance in form is offered by 

 certain phases of this parasite ^ to those of Try panomorpha 

 nocture when in the gnat. One side of the body appears 

 more delicate than the other, possesses a distinctly wavy 

 border, and is prolonged anteriorly, attached to the flagellum, 

 gradually tapering away however before the latter ter- 

 minates. 



There are one or two other important morphological points 

 to note in connection with these Herpetomonadine forms. In 

 many a vacuole can be easily demonstrated situated in the 

 cytoplasm near the anterior flagellate end. In H. muscge- 

 domestic^e and H. gracilis (tig. 36 b) this structure is con- 

 tractile or pulsatile, but in H. subulata (fig. 3G e), a more 

 specialised type, it appears constant (non-contractile), though 

 probably still retaining its original excretory function. A 

 feature in H. gracilis is the occurrence of a number of 

 deeply-staining grains in the cytoplasm, doubtless comparable 

 to the chromatoid grains described in many Trypanosomes. 

 In this parasite they are all in the non-fiagellate part of 

 the body behind the nucleus. 



Lastly, it is to be remembered (1) that all the parasites 

 mentioned have also gregariniform resting-phases, in which 

 the locomotor apparatus may become reduced to a short 

 rostrum serving for attachment to a host-cell, or may entirely 

 vanish (see fig. 36 d and g) ; and (2) that H. subulata, as 

 well as certain other species, becomes united in rosettes in 

 which the parasites are all attached by the anterior end. 



From these considerations it appears scarcely open to doubt 

 that an intimate degree of relationship exists between 



' Unfortunately the only figures at present available are not very good. 



