STRUCTURE AND OCCURRENCE. 249 



is said by older observers to consist of six or seven short hairs, which are 

 in constant vibration. The parenchyma is colourless and clear, with 

 fine granules in the interior (Fig. 125). 



As will be seen from the foregoing diagnosis, our knowledge of the 

 vaginal Monads has only reached a satisfactory state in consequence 

 of Blochmann's researches. Even the num- 

 ber of the flagella was uncertain, being 

 supposed to vary from one to three. Where 

 apparently only one is present, they have 

 probably coalesced, as may be guessed from " 

 the fact that in such cases the flagella are 

 sometimes represented as divided at the 

 end. A fine longitudinal line running FIG. i25.Trickomonas 



j ,, .,..., alls. (After Kolliker.) 



down near the accessory cilia is interpreted 

 as the mouth, with what accuracy is a moot-point; it might more 

 probably represent the point of attachment of the ciliary comb. 

 [In the anterior end is a distinct nucleus (Blochmann)]. 



Some investigators assert that they have seen forms of Trichomonas 

 which were in a state of greater or less expansion, and were furnished 

 with stiff, bristly hairs, and have even tried to make a particular species 

 of them. To all appearance, however, these statements deserve but 

 little confidence. These parasites are extremely sensitive to water 

 and watery solutions, and generally perish quickly after the applica- 

 tion of sucli fluids. They then swell up, and coagulate into a more or 

 less globular mass motionless, and robbed of its appendages. As these 

 much altered forms have a certain resemblance to ciliated cells, it is 

 very likely that they were the origin of the above statements, just as 

 in earlier times they gave rise to the very widely spread opinion, held 

 by many weighty authorities (such as Valentin, Siebold, and others), 

 that the Trichomonas of Donne represented only isolated and altered 

 ciliated cells. 



In their natural condition the vaginal Monads show a quick and 

 lively motion, which, when the parasites are present in great numbers, 

 almost gives the impression of the so-called Infusorian "swarming," and 

 especially since the animals frequently crowd round a lump of mucus, 

 or are united into a group by means of their tails. The motion also 

 changes, more or less, as the body turns first right, then left, in con- 

 sequence of the influence exerted on it by the undulations of the 

 ciliary comb. [These forms have also a creeping motion like Euglena.] 

 If the surrounding temperature be reduced, the motion becomes 

 slower, and entirely ceases a few minutes after 9 C. is reached, but 

 recommences as soon as heat is again applied. 



