FLAGELLATE INFUSORIA AND ALLIED ORGANISMS. 93 



Shortly before or at the instant of appearance of the mark of 

 fission the nucleus appears band-like and elongated across 

 the body of the organism (fig. 20 c). There also appears to 

 be a longitudinally-striped differentiation of the inner sub- 

 stance of the nucleus, and a swelling of this stripe into knot- 

 like thickenings is to be clearly seen at one of their ends. 

 After the fission had made some progress the nucleus thinned 

 in the middle, the ends became swollen, and in each a dis- 

 tinct inner body made its appearance, connected by a delicate 

 thread with the one on the other side (fig. 20 f). In a still 

 more advanced condition the two nuclei, which had become 

 quite rounded, were only united by a delicate thread of con- 

 siderable length. 



Lophomonas, Stein (' Sitzunbericht. der. konigl. bohm. 

 Gesellsch. d. Wissensch. Jahrg.,' 1860, pp. 49, 50). 



Lophomonas blattarum. Stein (loc. cit.). 



These highly interesting parasitic Flagellate forms were 

 found by Stein in the rectum of Blatta orientaUs. The 

 author is able to confirm Stein's observations in every respect, 

 so far as the few specimens seen by him will allow. The shape 

 of Lophomonas hlattarum is a roundish ovoid (Plate vi, fig. 

 21 b), only the smallest individuals possessing the more sphe- 

 rical form (fig. 21 a) described as being most common by Stein. 

 The author has investigated these organisms in a dilute solu- 

 tion of albumen, and has by this means avoided the alterative 

 influence of water, whilst he has been able to preverve them 

 uninjured for more than twenty-four hours. 



The somewhat tapering anterior extremity is sharply trun- 

 cated, and it is from this point, which is sometimes very 

 distinct, and at other times very indistinct, that the tuft of 

 flagella which is so characteristic of the species arises. This 

 tuft consists of a great number of flagella ranged close to 

 each other which are in part twisted together into a tuft — 

 this is true chiefly for the middle and larger ones — which is 

 only broken up into the individual flagella at its extremity. 

 The outer flagella of the tuft are smaller and separate, and 

 vibrate freely in the surrounding fluid medium. The united 

 tuft, on the other hand, performs only occasionally lashing and 

 jerking movements. In exhausted and dying specimens the 

 cilia separate into confused tufts. The structure of the 

 anterior end carrying the tuft of flagella is very peculiar. A 

 round and somewhat dark body, the nucleus, is situated a 

 short distance behind the cluster of cilia ; it stains deeply 

 with carmine, and gives the impression of a homogeneous 

 plasmatic body in the living organism, but after treatment 



